Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF MONITORING AND CONTROLLING
TERMITES WITH HEAT-TREATED WOOD
BACKGROUND
[0001] Drying wood is known in the field of wood preparation
and preservation. There is a broad spectrum of processes that are utilized to
dry wood. One such process occurs naturally to wood maintained at
atmospheric conditions, such as with the aging of cut logs on a wood pile.
This drying reduces the water content of the wood, while the wood remains
susceptible to decay and cellular degeneration due to fungal pathogens, for
example. Other drying techniques utilize heated chambers, such as kilns,
maintained at elevated temperatures, such as those between about 40
degrees C (105 degrees F) and about 90 degrees C (195 degrees F), to more
quickly dry wood. Wood dried in this manner is conventionally utilized as
lumber, such as for construction projects and the like. Other conventional
drying processes utilize high-temperature steam to dry wood at temperatures
of between about 90 degrees C (195 degrees F) and about 150 degrees C
(302 degrees F). This temperature level provides shorter drying times and
more dimensionally-stable lumber, as compared with the previously discussed
processes. Such conventional lumber is typically marketed for sale having a
water content of between about 15 percent and about 18 percent. Once such
lumber is in use in an ambient environment for some time, such as in a frame
house, the wood has a water content of between about 10 percent and about
15 percent.
[0002] Another conventional wood drying process utilizes even
more elevated temperatures, such as between about 150 degrees C (302
degrees F) and about 215 degrees C (420 degrees F) to alter the color of the
wood itself. The upper limit on the heating can be higher than the 215
degrees C (420 degrees F) noted above, as long as the temperature remains
below the charring temperature of the treated wood. Such processing is
conventionally utilized to create the appearance of stained wood, without the
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use of chemical stains. Because such wood is superheated to elevated
temperatures, much of the water content is removed from the wood, bringing
water levels in the heat-treated wood to between about two percent and about
ten percent. Although this process is known in the art of wood preparation
and preservation, the wood product created by the process has not been used
conventionally as a medium for monitoring or controlling termites.
[0003] Moreover, conventional techniques and knowledge
regarding termite monitoring and controlling teach that this wood would not be
of use for monitoring and controlling termites. First, wood having a higher
water content, such as between about 10 percent and about 20 percent is
conventionally thought to be more attractive to termites. Second, heat-
treating wood in this manner produces a heat-treated wood product that is
less hygroscopic than untreated wood or wood dried at lower temperatures.
As such, conventional wisdom regarding termite feeding would indicate that
such wood would not be attractive to termites because even with additional
water available (such as with a below ground installation), the heat-treated
wood will resist the absorption of water. Without absorbing water -
conventional wisdom goes - the termites will not be interested in feeding.
[0004] In contrast with this conventional thinking
regarding termite food selection and contrary to past understanding and
teaching regarding termite wood preferences, the present invention utilizes
such heat-treated wood with relatively lower levels of water and less
hygroscopy than conventionally treated wood with unexpected success as a
food source and attractant for termites. Additional benefits include enhanced
resistance to microbiological attack and an increased amount of extractable
compounds attractive to foraging termites. A termite monitoring and control
method utilizing this heat-treated wood thus provides unexpected benefits
over more conventional wood-based termite stations.
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SUMMARY
[0005] In one embodiment, a method of monitoring termite
populations in an area accessible to the termites generally comprises locating
in the area a wood that has been heat-treated to a temperature of greater
than about 150 degrees C (302 degrees F), and monitoring the heat-treated
wood for the presence of termites.
[0006] In another embodiment, a method of monitoring and
controlling termite populations in an area accessible to termites generally
comprises locating in the area a wood that has been heat-treated to a
temperature of at least about 150 degrees C (302 degrees F), and locating a
toxic bait in the area.
[0007] In another embodiment, a method of controlling termite
populations in an area accessible to termites generally comprises locating in
the area a toxic bait comprising wood that has been heat-treated to a
temperature of at least about 150 degrees C (302 degrees F) and a toxicant.
[0008] In another embodiment, a method of at least one of
monitoring and controlling termite populations in an area accessible to the
termites according to one embodiment generally comprises locating in the
area a heat treated wood extract, the extract being extracted from wood that
has been heat-treated to a temperature of greater than about 150 degrees C.
[0009] In another embodiment, a method of at least one of
monitoring and controlling termite populations in an area accessible to the
termites generally comprises locating a termite station housing generally at
an
area accessible to termites, the termite station housing having at least one
opening therein providing communication between an interior and the exterior
of the termite station housing. An aggregation base is positioned within the
interior of the housing. A heat treated wood extract is deposited at least one
of in the interior of the housing and in the environment exterior of the
housing,
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with the heat treated wood extract having been extracted from wood that has
been heat-treated to a temperature of greater than about 150 degrees C.
[0010] In another embodiment, an attractant for use in
monitoring and controlling termite populations generally comprises a heat
treated wood extract, the extract being extracted from a hot water extraction
of wood that has been heat-treated to a temperature of greater than about
150 degrees C.
[0011] In another embodiment, a method of monitoring and
controlling a termite population generally comprises locating a termite
station
housing generally at an area accessible to termites. The termite station
housing has at least one opening therein providing communication between
an interior and the exterior of the termite station housing. A particulate
heat
treated wood is deposited in the station housing, with the heat treated wood
having been heat treated to a temperature of greater than about 150 degrees
C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Fig. 1 is a perspective view of one embodiment of a
termite station with a lid of a container of the termite station illustrated
in a
closed position of the lid;
[0013] Fig. 2 is a perspective view similar to Fig. 1 with the
termite station in a storage configuration thereof with a cartridge disposed
in
the container and the lid of the container illustrated in an open position;
[0014] Fig. 3 is a top plan view of the termite station container
with the container lid in its open position;
[0015] Fig. 3A is a side elevation thereof, with an access tab
removed from the container;
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[0016] Fig. 3B is a front elevation thereof, with another access
tab removed from the container;
[0017] Fig. 3C is a top perspective view thereof;
[0018] Fig. 4 is a bottom perspective view of the container of
Fig. 3;
[0019] Fig. 5 is a front elevation of the termite station cartridge,
with the cartridge removed from the container;
[0020] Fig. 6 is an exploded perspective of the termite station
cartridge of Fig. 5;
[0021] Fig. 6A is a view similar to Fig. 6 with the cartridge only
partially exploded;
[0022] Fig. 7 is a top plan view of a holder of the cartridge, a
cover, an aggregation member and a bait matrix of the cartridge having been
omitted to reveal internal construction of the holder;
[0023] Fig. 8 is a bottom plan view of the cartridge holder;
[0024] Fig. 9 is a side elevation of the termite station in an
operating configuration thereof, with the lid in its closed position and with
a
side panel of the container and portions of the cartridge holder and cover
broken away, and with an access tab removed from the container;
[0025] Fig. 10 is a perspective view of the termite station
container (with the cartridge removed) fastened on a vertical mounting surface
along a termite tunnel that extends up the mounting surface;
[0026] Fig. 11 is an enlarged top plan view of the encircled
portion of Fig. 10;
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[0027] Fig. 12 is a cross-section taken in the plane of line 12-
12 of Fig. 11;
[0028] Fig. 13 is an enlarged view of a container opening and
access tab located along a side of the container;
[0029] Fig. 14 is an enlarged view of a container opening and
access tab located at a corner of the container;
[0030] Fig. 15 is a top plan view of a termite station container
according to a second embodiment of a termite station, with a lid of the
container in its open position;
[0031] Fig. 15A is a side elevation thereof;
[0032] Fig. 15B is a front elevation thereof;
[0033] Fig. 16 is a perspective of an embodiment of the pest
control device of the present invention;
[0034] Fig. 17 is an exploded perspective of the pest control
device of Fig. 16;
[0035] Fig. 18 is a perspective of an aggregation base used
with the pest control device of Fig. 16;
[0036] Fig. 19 is an exploded perspective of a container used
in the pest control device of Fig. 16;
[0037] Fig. 20 is an exploded perspective of a bait container
similar in construction to the monitoring container of Fig. 19 with a bait
placed
therein;
[0038] Fig. 21 is a perspective of a cup portion of the container
of Fig. 19;
[0039] Fig. 22 is another perspective of the cup of Fig. 19; and
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[0040] Fig. 23 is a perspective of a lid portion of the container
of Fig. 19.
DETAILED DESCRIPTION
[0041 ] With reference now to the drawings, and in particular to
Fig. 1, one embodiment of a termite station is generally indicated at 21 and
illustrated in the form of an above-ground termite station in what is referred
to
herein as a storage configuration, such as upon initial packaging or periods
of
non-use of the termite station. The termite station 21 of this embodiment is
an
above-ground termite station in that it is intended to be used above soil,
such
as by being secured on a suitable above-ground mounting surface including,
without limitation, on top of soil, on a generally horizontal surface, a
sloped
surface or a vertical mounting surface (such as an interior or exterior wall
of a
house or building, a tree, a fence post or picket, and the like). The termite
station 21 generally comprises a rectangular box-shaped container, indicated
generally at 23, having a base panel 25 (or bottom panel in the orientation
illustrated in Fig. 1, broadly referred to herein as a base of the container),
longitudinally opposite end panels 27, laterally opposite side panels 29 and a
lid 31 (broadly, a closure) together defining an interior space 33 (Fig. 3) of
the
container. The end panels 27 and side panels 29 of the illustrated
embodiment together broadly define what is referred to herein as a side of the
container 23. Accordingly, it is understood that the container 23 may be other
than rectangular box-shaped, such as cylindrical (which would have a
generally annular side) or another suitable shape, as long as the base panel
25, the side and the lid 31 are configured and arranged to together define the
interior space 33 of the container.
[0042] The base panel 25 suitably has an outer surface 35
(Fig. 4) that faces a mounting surface M (Fig. 10) upon which the termite
station is mounted, and an inner surface 37 (Fig. 3) that faces inward of the
container and in part defines the interior space 33 of the container. The
illustrated base panel 25 is rectangular and is suitably generally flat, or
planar,
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so that substantially the entire outer surface 35 of the base panel is in
opposed and abutting relationship with the mounting surface M upon
mounting of the termite station 21. It is understood, however, that the base
panel 25 may be other than generally flat or planar such as by having a
concave, convex or other non-planar configuration, so that less than the
entire
outer surface 35 of the base panel abuts against the mounting surface,
without departing from the scope of this invention. The illustrated end panels
27 and side panels 29 are also flat, or planar and are oriented generally
perpendicular to the base panel 25. Alternatively, the end panels 27 and/or
the side panels 29 may be other than perpendicular to the base panel 25,
such as angled outward or angled inward relative thereto, and may be other
than flat, or planar. It is also contemplated that the end panels 27 and/or
side
panels 29 may be curved, such as concave or convex, or other non-planar
configuration. In one suitable embodiment, the container 23 may be
constructed of a durable material that is not preferentially fed upon by
termites, such as, for example, an acrylic or high strength plastic. In
another
suitable embodiment the container 23 may be constructed of a biodegradable
material that is not preferentially fed upon by termites, such as, for
example,
biopolymers derived from organic materials. In a particularly suitable
embodiment the container 23 is substantially opaque, although it is
understood that the container may instead be generally translucent or even
transparent.
[0043] With particular reference to Figs. 3, 4 and 10, the base
panel 25 is more suitably configured to permit mounting of the base panel
itself (and hence the termite station container 23), to the desired mounting
surface M. For example, in the illustrated embodiment at least one and more
suitably a plurality of openings 39 are formed in the base panel 25 in spaced
relationship with, i.e., inward of, a peripheral edge 41 (Fig. 4) of the base
panel (the "peripheral edge" of the base panel being defined as the
intersection of the base panel with the side, e.g., the end panels 27 and the
side panels 29). As seen best in Fig. 11, the illustrated openings 39 each
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having a generally plus-sign or cross shape (i.e., comprised of intersecting
elongate slots). However, it is contemplated that these openings 39 may be
of any shape without departing from the scope of this invention. It is also
contemplated that the openings 39 need not all be of the same shape. Eleven
such openings 39 are formed in the base panel 25 of the illustrated
embodiment, with one of the openings being centrally located (both
longitudinally and laterally) in the base panel. While the spacing between all
eleven openings 39 is non-uniform, it is understood that the spacing between
the openings may instead be uniform. It is also understood that more or less
than eleven openings 39 may be formed in the base panel 25, including a
single opening. Additionally, where multiple openings 39 are present in the
base panel 25, as in the illustrated embodiment, the pattern or arrangement of
the openings may be other than that illustrated in Figs. 3 and 4.
[0044] These base panel openings 39 are used to mount the
base panel 25 (and hence the container 23) on the mounting surface M using
suitable fasteners such as screw fasteners 43 (Fig. 10) that extend in part
through the openings and into the mounting surface. As illustrated in Fig. 11,
each of the openings 39 is suitably sized in planar dimension (e.g., length
and
width, or diameter where the opening is circular) substantially larger than
the
cross-section of the shaft of the fastener 43 so that the fastener may extend
through the opening along a relatively large fastener location range. The term
"fastener location range" is intended herein to mean the length of open space
along which the fastener 43 may be located in a particular direction within
the
opening 39. In one suitable embodiment, for example, the fastener location
range provided by the opening 39 is at least about two times the maximum
diameter of the shaft of the fastener (i.e. the portion that extends through
the
opening upon fastening the base panel on the mounting surface), more
suitably at least three times the maximum diameter, and even more suitably at
least about 4 times the maximum diameter. In other embodiments the
fastener location range provided by the opening 39 is the range of about 2 to
about 6 times the maximum diameter of the shaft of the fastener, more
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suitably in the range of about 3 to about 6 times and even more suitably in
the
range of about 4 to about 6 times the maximum diameter of the shaft of the
fastener. In another example, the fastener location range provided by the
opening 39 and fastener 43 illustrated in Fig. 11 is at least about 0.25
inches
(about 6.35 mm), and is more suitably in the range of about 0.25 inches to
about 1.25 inches.
[0045] Providing a plurality of such openings 39 in the base
panel 25 allows the base panel (and hence the termite station 21) to be
arranged at a desired location on the mounting surface M, such as with one or
more of the openings located over an opening (not shown) formed by termites
in the mounting surface, while providing sufficient additional openings
through
which fasteners 43 may extend through the base panel into the mounting
surface at a more stable (e.g., less damaged) or stronger segment of the
mounting surface. Thus, in such an embodiment the number of openings 39
exceeds the number of fasteners used to fasten the base panel on the
mounting surface M by at least one. The openings 39 also allow the termite
station 21 to be secured to the mounting surface M by passing the fasteners
43 through a single structural member of the container 23, i.e., the base
panel
25, as opposed to multiple components thereof. For example, the lid 31 of the
container 23 is free of openings that may otherwise be used as in the case
with conventional designs because it is unnecessary for mounting fasteners to
extend through the lid. This arrangement makes it easier to visually place the
termite station 21, and in particular the base panel 25, in the desired
location
on the mounting surface M and also allows opening and closing of the lid 31
while the termite station remains mounted on the mounting surface, and in
particular without having to loosen or remove the mounting fasteners.
[0046] The openings 39 in the base panel 25 also provide
multiple entry points for the ingress and egress of termites to and from the
interior space 33 of the container 31 through the base panel 25. To this end,
the base panel is openings 39 are generally chamfered, or tapered outward
(e.g., expanding in planar dimension) from the base panel outer surface 35 to
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the inner surface 37 thereof as illustrated in Fig. 12 so that the tapered
portions act as entry ramps 45 into the interior space 33 of the container 23,
thereby reducing or minimizing discontinuities encountered by termites
entering the container. As an example, in one embodiment the tapered
openings 39 define a ramp 45 angle from the outer surface 35 to the inner
surface 37 of the base panel 25 in the range of about 15 to about 60 degrees,
and more suitably of about 45 degrees.
[0047] Peripheral (i.e., side entry) openings 47 are formed in
the end panels 27 and side panels 29 (i.e., broadly, the side) of the
illustrated
container 23 in spaced relationship with each other about the periphery of the
container. More suitably, these peripheral openings 47 extend from the
respective end panels 27 and side panels 29 to the base panel 25 (i.e., to the
corners where the end panels and side panels meet the base panel), to allow
termites to enter the interior space 33 of the container 23 from the sides
thereof, such as along a termite tunnel formed along the mounting surface M
(Fig. 10), instead of from behind the base panel (i.e., other than through the
openings 39 formed in the base panel). In a particularly suitable embodiment,
the peripheral openings 47 formed in the end panels 27 and side panels 29
continue into the base panel 25 so that termites that pass through the
peripheral openings are disposed further within the interior space 33 of the
container 23 before coming into contact with the container (i.e., with the
base
panel). However, it is not necessary that the peripheral openings 47 extend
into the base panel 25 to remain within the scope of this invention. It is
also
contemplated that the base panel 25 may be chamfered or tapered where the
peripheral openings 47 contact the base panel, such as in a manner similar to
the tapered openings 39 formed in the base panel.
[0048] As best seen in Figs. 3 and 4, the peripheral openings
47 formed in one end panel 27 are aligned with corresponding peripheral
openings in the opposite end panel and peripheral openings in one side panel
29 are aligned with corresponding peripheral openings in the opposite side
panel. The peripheral openings 47 formed in the side (e.g., the end and side
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panels 27, 29) of the container 23 allow the termite station 21 to be mounted
on a mounting surface M along a termite tunnel T, such as by breaking the
tunnel and placing the base panel 25 against the mounting surface within the
broken away portions of the tunnel aligned with one or more of the peripheral
openings as illustrated in Fig. 10. It is understood that the number of
peripheral openings 47 provided in the container 23 may be more or less than
that of the illustrated container 23, including only a single peripheral
opening,
without departing from the scope of this invention.
[0049] In the illustrated embodiment (as best illustrated in Fig.
4), the peripheral openings 47 are at least partially closed by respective
access closures 50 that can be removed from the container to provide access
through the peripheral opening. This allows the container to be generally
sealed about its periphery except at those peripheral openings 47 that are
aligned with the termite tunnel as in Fig. 10. With particular reference to
Fig.
13 (illustrating one access closure 50 located along the side of the termite
station 21) and Fig. 14 (illustrating one access closure located at a corner
of
the termite station), the illustrated access closures 50 are removeably
connected, and more suitably frangibly or rupturably connected to the
container 23 at the peripheral openings 47 so that the closures may be
removed (such as manually or by using a suitable punch tool, pliers, screw
drive or other suitable tool) from the container to provide access to the
interior
space of the container. For example, in the embodiments of Figs. 13 and 14,
the access 50 closure is frangibly connected to the container 23 at the
respective peripheral opening 47 at three connecting webs 52. The access
closure 50 is generally L-shaped in cross-section, having an upstanding
portion 54 that closes a portion of the peripheral opening in the side of the
container 23 and a base portion 56 that closes a portion of the peripheral
opening in the base panel 25 of the container. In a particularly suitable
embodiment the access closure 50 is formed integrally with (e.g., molded as
part of) the container 23.
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[0050] It is contemplated, however, that the access closures
50 may be formed separate from and removeably connected to the container
at the peripheral openings 47, such as thermal welding, adhesive or other
suitable connecting technique without departing from the scope of this
invention. It is also understood that in some embodiments the access
closures 50 may be refastenably connected to the container 23 (such as, for
example, by adhesive, hook and loop fasteners or other suitable mechanical
fasteners) so that the termite station 21 can be reconfigured and reused in
treating a different termite tunnel or other infestation within the scope of
this
invention.
[0051] In another suitable embodiment, illustrated in Figs. 15,
15A and 15B, the access closures 50 are omitted from the container 23.
[0052] One or more raised spacing elements (e.g., nubs 49 as
illustrated in Fig. 3, ribs, bumps, or other suitable locating elements) are
provided on the inner surface 37 of the base panel 25 so as to extend out
from the plane of the base panel into the interior space 33 of the container
23.
In particular, the spacing elements 49 are formed (e.g., molded in the
illustrated embodiment) integrally with the base panel 25 of the container 23.
However, these spacing elements 49 may alternatively be formed separate
from the base panel 25 and secured to the inner surface 37 thereof, such as
by adhesive, welding or other suitable securement technique without
departing from the scope of this invention. It is understood, though, that
these
spacing elements 49 may be omitted without departing from the scope of this
invention.
[0053] Referring back to Fig. 1, the lid 31 (broadly, a closure
for the container 23) is suitably positionable between a closed position (Fig.
1)
and an open position (Fig. 2) in which the interior space 33 of the container
23
is accessible. More particularly, the illustrated lid 31 is hinged to the
peripheral side wall of the container (e.g., to one of the container side
panels
29 as in the illustrated embodiment, or to one of the end panels 27) for
hinged
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motion relative thereto, and more suitable relative to the base panel 25,
between the closed and open positions of the lid. For example, as seen in
Fig. 3A, the lid 31 may be hinged to the side panel 29 in the manner of a
"living hinge" - in which the lid is formed (e.g., molded) integrally with the
side
panel along a thinned or scored connecting web 53 that is sufficiently
flexible
to allow hinged motion of the lid relative to the side panel. It is
understood,
though, that the lid 31 may be formed separate from the end panels 27 and
side panels 29 and mechanically hinged thereto by a suitable hinge
mechanism (not shown) without departing from the scope of this invention.
Referring to Fig. 3, a conventional latch and catch arrangement is provided
(e.g., with one or more latch members 55 being provided on the lid 31 as in
the illustrated embodiment and a corresponding catch or catches 57 being
provided on the side panel 29 and/or end panel 27 of the container 23, or vice
versa) for releasably securing the lid in its closed position.
[0054] In other embodiments, it is contemplated that the lid 31
may instead be formed separate from the rest of the container 23 and be
entirely placeable on and removable from the rest of the container. It is also
understood that any suitable releasable securement arrangement other than a
latch and catch arrangement may be used to releasably secure the lid 31 it its
closed position and remain within the scope of this invention. While in the
illustrated embodiments herein the side (i.e., the end and side panels 27, 29)
of the container 23 is secured to (and more suitably formed integrally with)
the
base panel 25, it is contemplated that the side may instead be secured to the
lid 31 and hinged to the base panel 25 for positioning along with the lid
between the closed and open positions thereof to provide access to the
interior space 33 of the container.
[0055] A cartridge 51 is suitably sized and configured for
disposition at least in part within the container 23 and more suitably
entirely
within the interior space 33 of the container in the closed position of the
container lid 31. With particular reference to Fig. 6, the cartridge 51
comprises one or more internal components, and in the illustrated
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embodiment all of the internal components, of the termite station 21. For
example, in the illustrated embodiment the cartridge 51 comprises an
aggregation member (indicated generally at 61), at least one bait matrix
(indicated generally at 63) separate from the aggregation member, and a
holder (indicated generally at 65) for holding the aggregation member, bait
matrix and holder in assembly for insertion in and/or removal from the
container 23 as a single unit. It is understood, however, that the cartridge
51
may comprise the holder 65 and only the aggregation member 61 or only the
bait matrix 63 without departing from the scope of this invention. In such an
embodiment, it is contemplated that the component omitted from the cartridge
51 may be disposed otherwise within the interior space 33 of the container 23
separate from the cartridge, or it may be disposed exterior of the container,
or
it may be omitted altogether.
[0056] The aggregation member 61 in one embodiment
comprises an attractant, and more suitably what is referred to herein as a
non-physical attractant. A "non-physical" attractant is intended to refer
herein
to an attractant that does not require physical contact by a termite to induce
foraging. For example, in one particularly suitable embodiment the non-
physical attractant comprises a wood that has been heat treated at an
elevated temperature, such as at least about 150 degrees C (302 degrees F)
and more suitably between about 150 degrees C and 215 degrees C (420
degrees F).
[0057] Wood is an organic material found as the primary
content of the stems of woody plants (e.g., trees and shrubs). Dry wood is
composed of fibers of cellulose (from about 40 percent to about 50 percent by
dry weight) and hemicelluloses (from about 20 percent to about 30 percent by
dry weight) held together by lignin (from about 25 percent to about 30 percent
by dry weight). Wood also contains extractives, which are compounds that
can be extracted using various solvents and are often less than 500
grams/mole in molecular weight. In general, these extractives constitute from
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about two percent to about eight percent (dry weight) of the wood
components.
[0058] Cellulose is the most abundant component in wood and
plays a major role in giving wood its mechanical strength. A molecule of
cellulose consists of R-D-glucose units bonded with R(1 ---> 4) lingages to
form
a long linear chain and has a molecular weight that ranges from several
thousand to many million grams/mole. The molecular chains in cellulose form
elementary fibrils or micelles. The micelles align with the cellulose fibrils
oriented in the same direction and are tightly packed together. Cellulose
elementary fibrils are then layered together in parallel with hemicelluloses
and
pectins in between to form microfibrils. When the microfibrils are aggregated
in larger bundles and lignin impregnated within the structure, fibrils are
generated, which in turn form wood fibers.
[0059] Hemicelluloses comprise from about 20 percent to
about 30 percent by dry weight. Smaller than cellulose molecules, the
average molecular weight of hemicelluloses range from about 10,000
grams/mole to about 30,000 grams/mole. The composition of hemicelluloses
varies between hardwoods (i.e., oak, mahogany) and softwoods (i.e., pine,
cedar). The hemicelluloses of hardwoods are predominantly of
glucuronoxylan (from about fifteen percent to about 30 percent) and to a
minor extent glucomannan (from about two percent to about five percent).
The hemicelluloses of softwoods consists predominantly of
galactoglucomannan (about twenty percent) and smaller amounts of
arabinoglucuroxylan (from about five percent to about ten percent).
[0060] Pectins and starch are also found in wood, but typically
in minor amounts, less than about one percent each. Pectins resemble
hemicelluloses in structure and are found in the middle lamella, primary cell
wall and tori of bordered pits and also to a small extent in the fibril
structure.
Starch can be found in parenchyma cells serving as storage of nutrition for
the
living tree, and it consists of amylase and amylopectin.
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[0061 ] Lignin is an amorphous polymer with a wide variation in
configuration. Lignin is often considered to be the glue of the wood
structure.
The backbone of the lignin structure is based on three types of phenyl
propane units: guaiacyl, syringyl, and p-hydroxyphenyl. Softwoods consist
mainly of guaiacyl units and also to some extent of p-hydroxyphenyl units. In
contrast, hardwood lignins consist of syringly and guaiacyl units.
[0062] When wood is dried, these chemical compounds that
make up the structure of wood undergo various changes. In particular,
according to one embodiment herein, the aggregation member 61 comprises
wood dried at an elevated temperature of between about 150 degrees C (302
degrees F) and about 215 degrees C (420 degrees F), whereat these
chemical changes are different from those produced by drying at lower
temperature ranges, such as below about 150 degrees C (302 degrees F). In
another exemplary embodiment herein, the aggregation member 61
comprises wood that is dried at an elevated temperature of between about
185 degrees C (365 degrees F) and about 215 degrees C (420 degrees F). In
particular, it is believed that the heat-treated wood undergoes changes
affecting the available space for air and moisture in the wood. In particular,
the porosity and permeability of the wood is changed. The porosity defines
the ratio of the volume fraction of void space within a solid. The
permeability
defines the rate of diffusion of a fluid through a porous body.
[0063] It is believed that after such treatment the porosity may
increase as liquids and other compounds not strongly bound to the structure
of the wood are removed with the heating of the wood, such as by
evaporation. Taken alone, this change would indicate that such heat-treated
wood would be more hygroscopic than untreated wood, as there is more
available space within the wood. But this conclusion ignores the changes
also made to the permeability of the treated wood. Permeability exists where
cells and/or voids can interconnect to one another. For example, with a
hardwood, intervessel pitting can create openings in membranes, allowing for
improved permeability. It is believed that after such heat treatment, however,
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those membranes may become occluded or encrusted. Such occlusions
decrease overall permeability. Moreover, the pits may also become
aspirated, whereby the wood assumes a closed-cell structure that again
decreases overall permeability. It is also believed that such heat treatment
can cause substantial disconnection of adjacent microfibrils within the heat-
treated wood. Whereas with living or non-heat treated wood, these adjacent
microfibrils provide structures for transport of liquid through the wood via
normal translaminar vascular flow of phloem and xylem tissue. With their
detachment, a disconnection is created within the wood that impedes the flow
of liquids, thereby decreasing hygroscopy (i.e., increasing hydrophobicity).
It
is also believed that the increased wood shrinkage that occurs at the heat
treatment temperature can lead to increased detachment of adjacent xylem
tissue cells and adjacent phloem tissue cells (i.e., vascular cells), thereby
inhibiting liquid passage through normal pathways of tissue cells. As would
be understood by one skilled in the art, these changes depend upon the
starting porosity, permeability, and density of the wood, but it is believed
that
such changes are generally applicable to many wood species. Moreover,
such heat treatment processes may cause other changes to the structure and
nature of the wood not mentioned here without departing from the scope of
the embodiments of the present invention.
[0064] In addition to changes in hygroscopy and
hydrophobicity, wood heat-treated in this manner also includes changes
associated with other chemical compounds normally bound to the cellulose
materials in the wood. While not being bound to a particular theory, it is
believed that as part of the heat-treatment process, the bonds normally
binding these chemical compounds (e.g., volatile, semi-volatile, and naturally-
extractable compounds (e.g., aromatic compounds), such as compounds
derived from tannins, terpenes, and oils, among others) to the cellulose of
the
wood are broken, thereby allowing movement of the compounds more readily
from the wood and into the area surrounding the wood (e.g., soil), as
compared with conventional wood decay. As such, these chemical
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compounds may be extracted, or released, and more readily spread from the
wood, thereby attracting termites to the wood.
[0065] Heat-treatment of wood in this manner generally
proceeds as follows. First, the wood is dried to remove a substantial portion
of the liquid from the wood. In one embodiment, the drying process occurs in
a range from about 110 degrees C (230 degrees F) to about 175 degrees C
(345 degrees F). The dried wood is then heated to and maintained at an
elevated temperature, such as between about 150 degrees C (302 degrees F)
and about 215 degrees C (420 degrees F), and more suitably between about
185 degrees C (365 degrees F) and about 215 degrees C (420 degrees F). It
is contemplated that in other embodiments the elevated temperature at which
the wood is heat-treated may exceed 215 degrees C (420 degrees F) as long
as the temperature remains below the ignition temperature of the wood
specimen to inhibit charring or burning of the treated wood. The treated wood
is suitably maintained at this temperature for a time sufficient to undergo
the
changes described above. In one exemplary embodiment, the wood is
maintained at the elevated temperature for between about two hours and
about three hours. The dried wood material is then cooled by a suitable
cooling method such as air cooling, liquid cooling or other know method.
[0066] In one exemplary embodiment, the dried heat-treated
wood may then be partially rehydrated to increase the liquid content of the
cellulose material to levels of between about one percent and about eighteen
percent. In still another exemplary embodiment, the heat-treated wood may
be partially rehydrated to levels of between about one percent and about ten
percent. In yet another exemplary embodiment, the dried wood material may
be partially rehydrated to levels of between about two percent and about ten
percent. It is understood, however, that the heat-treated wood need not be
partially rehydrated, such that the liquid content in the dried wood is less
than
about one percent, without departing from the scope of this invention.
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EXPERIMENT
[0067] In this experiment, samples of aspen wood heat-treated
according to one suitable embodiment and conventionally-treated aspen wood
were evaluated to determine Reticulitermues flavipes termite feeding
preference between these wood samples.
[0068] The heat-treated wood was processed as follows. The
wood was cut to a common board dimension, such as a standard 2x4 plank
(i.e., cross section of about 38 millimeters (1.5 inches) by about 89
millimeters
(3.5 inches)). The wood was then placed within a kiln or high
temperature/pressure vessel. The temperature within the vessel was
increased rapidly to about 100 degrees C (212 degrees F) and held until the
wood uniformly reached approximately zero percent moisture content. The
temperature was then steadily increased to and maintained at about 185
degrees C (365 degrees F) for a period of about 120 to 180 minutes. After
drying, the temperature of the wood was decreased to between about 80
degrees C (176 degrees F) and about 90 degrees C (194 degrees F). A
steam spray was used during the cooling period to reduce the temperature of
the wood and to increase the moisture content of the wood to between two
percent and about ten percent. The entire heating and cooling down process
took approximately 36 hours to complete.
[0069] The conventionally-treated aspen wood was kiln dried
at a temperature of about 85 degrees C (185 degrees F) and about 90
degrees C (195 degrees F) for about five to six days. After drying, the
conventionally-treated aspen wood was allowed to cool to ambient.
[0070] The experiment was conducted utilizing both a choice
and a no-choice laboratory bioassay. The purpose of the study was to
determine the preference, based upon association and/or consumption,
between the two wood samples described above. With the choice laboratory
bioassay, 300 termites by weight with 20 grams (0.7 ounce) of sand at 12%
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moisture were added to a petri dish with an average weight across all
replications of an approximately 4 gram (0.141 ounce) portion of the two types
of wood located in respective opposite halves of the petri dish. The termites
were placed between the portions of wood and were allowed to move to and
consume the wood they preferred. After 31 days, the termites on or near
each of the pieces of wood were counted. In addition, the termites were
removed from the wood and the wood weighed to determine the amount
consumed. This choice test was repeated seventeen times with seventeen
sets of 300 termites and new wood samples.
[0071] For the no-choice bioassay, 300 termites by weight with
20 grams (0.7 ounce) of sand at 12% moisture were added to a petri dish with
an average weight across all replications of an approximately 4 gram (0.141
ounce) portion of one of the wood samples. The termites were placed across
from the portion of wood and were allowed to move freely within the test
chamber and consume the wood. After 31 days, the termites were removed
from the wood and the wood weighed to determine the amount consumed.
This choice test was repeated five times with five sets of 300 termites and
new wood samples for each of the two different types (heat-treated and
conventionally treated) of wood samples.
[0072] With respect to consumption in the choice bioassay, the
wood heat-treated at elevated temperatures realized a mean consumption
rate of 19.0 milligrams per gram of termites per day (19.0 milliounces per
ounce of termites per day) with a standard deviation of 2.9 over the seventeen
choice tests. In contrast, the conventionally-treated wood realized a
consumption rate of 15.1 milligrams per gram of termites per day (15.1
milliounces per ounce of termites per day) with a standard deviation of 5.0
over the seventeen choice tests. In the no-choice bioassay, the wood heat-
treated at elevated temperatures realized a consumption rate of 42.4
milligrams per gram of termites per day (42.4 milliounces per ounce of
termites per day) with a standard deviation of 1.6 over the five no-choice
tests. In contrast, the conventionally-treated wood realized a consumption
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rate of 37.5 milligrams per gram of termites per day (37.5 milliounces per
ounce of termites per day) with a standard deviation of 5.6 over the five no-
choice tests. Thus, for both the choice and no-choice bioassays, the wood
that was heat-treated at elevated temperatures realized greater consumption
rates than the conventionally-treated wood.
[0073] Moreover, when considering association, rather than
consumption, the mean number of termites over the seventeen choice
bioassay tests located in the half of the petri dish including the wood that
was
heat-treated at elevated temperatures was 183, with a standard deviation of
34. In contrast, the mean number of termites located in the other half of the
petri dish including the conventionally-treated wood was 72, with a standard
deviation of 40. Of the 300 termites included in each experiment, a mean of
47 died during the experiment. This result occurred even though the wood
that was heat-treated at elevated temperatures was significantly drier, having
less internal moisture content, than the conventionally-treated wood. This
indicates, rather unexpectedly, that the reduced moisture content of the wood
heat-treated at elevated temperatures did not deter the termites from feeding
on the wood and even more unexpectedly it attracted more of the termites
due to the physical and/or chemical characteristics of the wood. Termites in
this study demonstrated significantly greater attraction to or preference for
the
wood heat-treated at elevated temperatures as compared to the
conventionally treated wood.
--------------
[0074] In view of the above Experiment, the increased non-
physical attraction and association preference of the wood heat-treated at
elevated temperatures may significantly enhance the efficacy of a termite
monitoring and/or baiting station that includes such a wood. As a more
particular example, the illustrated aggregation member 61 comprises a solid
wood block 67 that has been heat-treated at elevated temperatures as
discussed above. It is understood, though, that the heat-treated wood from
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which the aggregation member 61 is made may alternatively be in a mulch
form, a powder form or other suitable form. The aggregation member 61 is
also suitably free from toxicant. For example, the above-described heat-
treated wood has no added or natural toxicants.
[0075] In other embodiments, it is contemplated that the
aggregation member 61 may instead comprise a non-toxic physical attractant,
i.e., an attractant that once contacted by a termite promotes further foraging
by termites. Suitable examples of such physical attractants include, without
limitation, paper, cardboard, wood (e.g., other than wood that has been heat-
treated in as described above) and other cellulose materials. Additionally an
agar matrix alone or combined with sugars (i.e., xylose, mannose, galactose)
and/or purified cellulose materials may be used as the aggregation member
61 to attract termites due to its moisture content and/or feeding attractant.
[0076] The bait matrix 63 suitably comprises a non-toxic
attractant and may or may not carry a toxicant for eliminating or suppressing
termite infestations. As one example, the illustrated bait matrix 61 comprises
a purified cellulose powder compressed into one or more tablets 69. Without
toxicant added to the bait matrix 61, the bait matrix may be suitably used to
monitor for the presence of termites in the area of the termite station 21.
Toxicant, if added to the bait matrix 61, is suitably one or more of a delayed-
action type toxicant, or an insect growth regulator, pathogen or metabolic
inhibitor. One such toxic bait matrix 61 is disclosed in co-assigned U.S.
Patent No. 6,416,752 entitled "Termite Bait Composition and Method", the
entire disclosure of which is incorporated herein by reference. It is
understood that other suitable known monitoring and/or toxic bait matrix
materials and/or compositions may used without departing from the scope of
this invention. In the illustrated embodiment, four such toxic bait matrix
tablets 69 are used in the cartridge 51. However, it is contemplated that any
number of bait matrices, including a single bait matrix, may be used without
departing from the scope of this invention.
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[0077] The illustrated cartridge holder 65 comprises a cup
portion 71 configured generally as a pair of cylindrical cups 73 (e.g., each
having a closed end 75, an open end 77 and a side wall 79 extending
therebetween) with overlapped segments so that the cup portion defines a
generally 8-shaped bait matrix pocket 81. The pocket 81 is suitably sized and
configured for at least receiving, and more suitably for receiving and
retaining,
the bait matrix 63 therein and more suitably for receiving and retaining one
or
more of the illustrated circular tablets 69 therein. For example, the figure 8-
shaped pocket 81 of Figs. 6 and 7 is suitably capable of receiving and
retaining therein at least two circular bait matrix tablets 69 arranged in
side-
by-side relationship (e.g., one in each generally cylindrical cup 73 that
defines
the pocket), and is more suitably sized (e.g., in depth) to receive a stacked
pair of the tablets in each of the cups, with the exposed surfaces of the
uppermost bait matrix tablets being generally flush with the open ends 77 of
the cups. It is understood, however, that the pocket 81 may be shaped other
than as illustrated in Fig. 7 and that the tablets 69 or other bait matrix
disposed in the pocket may be shaped other than circular without departing
from the scope of the invention. Additionally, it is contemplated that the
cartridge holder 65 may comprise two or more separate pockets instead of the
single pocket 81 illustrated in Fig. 7.
[0078] A plurality of projections, such as in the form of ribs 83
in the illustrated embodiment, are disposed lengthwise along the inner surface
of each cup side wall 79 to extend laterally inward of the pocket 81 formed by
the generally cylindrical cups 73. For example, the ribs 83 illustrated in
Figs.
6 and 7 extend lengthwise from the closed end 75 of the cup 73 to the open
end 77 thereof and project sufficiently inward from the inner surface of the
cup
side wall 79 to provide an interference, or friction fit of the bait matrix
tablets
69 within the pocket 81 to positively retain the tablets in the pocket. It is
understood, though, that the ribs 83 need not extend the full length from the
closed ends 75 to the open ends 77 of the cups 73 to remain within the scope
of this invention. It is also contemplated that a greater or lesser number of
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ribs 83 or other suitable projections may be used to retain the bait matrix 61
or
matrices within the cartridge holder pocket 81. Standoff elements in the form
of a plurality of nubs 85 (Figs. 6 and 7) are provided on the inner surface of
the cup portion 71 at the closed end 75 of each of the cups 73 to extend into
the respective pocket 81. The standoff elements 85 space the tablets 69 from
the closed ends 75 of the cups 73 to allow termites to move therebetween
within the pocket 81. In a particularly suitable embodiment, the standoff
elements 85 are provided by corresponding sockets 87 (Fig. 8) formed in the
outer surface of the closed end 75 of each of the cups 73. These sockets 87
are configured and arranged to receive the spacing elements 49 that extend
out from the inner surface 37 of the base panel 25 to allow the cartridge to
seat sufficiently into the container 23 in the storage configuration of the
termite station 21 so that the lid of the container can be closed.
[0079] Still referring to Figs. 6 and 7, the cartridge holder 65
also has a generally rectangular tray portion 91 formed integrally with and
extending around the cup portion 71 of the cartridge holder to receive, and
more suitably to receive and retain the aggregation member 61 in the
cartridge holder. A support panel 93 (e.g., bottom) of the illustrated tray
portion 91 (which also includes a peripheral side wall 95 defining the depth
of
the tray portion) is suitably spaced lengthwise from the open ends 77 of the
generally cylindrical cups 73 so that the aggregation member 61 held by the
tray portion at least in part surrounds the cups in which the bait matrix 63
is
disposed. It is contemplated, however, that the support panel 93 of the tray
portion 91 may be located at substantially any position between the closed
ends 75 and the open ends 77 of the cups 73 without departing from the
scope of the invention. In one particularly suitable embodiment, the
aggregation member 61 and the tray portion 91 of the holder 65 are sized
relative to each other to provide an interference or friction fit of the
aggregation member in the tray portion to thereby retain the aggregation
member in the holder. As best seen in Fig. 6, the heat-treated wood block 67
that defines the aggregation member 61 of the illustrated embodiment is
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generally rectangular and has a central opening 97 so that when seated in the
tray portion 91 of the holder 65 the wood block surrounds the cups 73 of the
cup portion 71 proximate the open ends 77 of the cups while leaving centrally
exposed the bait matrix tablets 69.
[0080] Suitable spacing structure is provided to space at least
a portion of the aggregation member 61 from the base panel 25 in what is
referred to herein as an operating configuration (Fig. 9) of the termite
station
21 to permit termites to readily move between the aggregation member and
the base panel. For example, in the illustrated embodiment of Fig. 6 the
spacing structure comprises four standoff elements 99 secured to and more
particularly formed integrally with the heat-treated wood block 67. It is
understood that more or less than the four illustrated standoff elements 99
may be provided. The spacing structure may alternatively be formed into the
aggregation member 61, such as grooves, slots or other voids formed in the
outer surface of the wood block 67, so that less than the entire outer surface
of the wood block (e.g., where the grooves, etc. are located) lies against the
base panel 25 in the operating configuration of the termite station 21. In
other
contemplated embodiments, suitable spacing structure may be formed
integrally with the inner surface 37 of the base panel 25, or it may be formed
separate from and attached thereto, at one or more locations contacted by the
aggregation member 61 in the operating configuration of the termite station
21. While less preferred, it is also understood that other suitable spacing
structure may be formed and remain separate from both the cartridge 51 and
the container 23 and disposed therebetween in the container to space at least
a portion of the aggregation member 61 from the base panel.
[0081 ] As best seen in Fig. 9, the spacing structure (e.g.,
standoff elements 99 in the illustrated embodiment) spaces the outer surface
of the aggregation member 61 (which faces the inner surface 37 of the base
panel 25 in the operating configuration of the termite station 21) a distance
sufficient to allow termites to move freely (i.e., without having to forage
through the aggregation member) between the aggregation member and the
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base panel. More suitably, the spacing between the aggregation member 61
and the base panel 25 is such that the termite's antennae can remain in
contact with the aggregation member as the termite moves past the
aggregation member. As an example, the spacing structure in one
embodiment may space the aggregation member 61 from the base panel 25 a
distance in the range of about 0.20 cm to about 0.6 cm. The spacing
elements 49 on the base panel 25 suitably space the bait matrix 63 (e.g.,
tablets 69) from the base panel to allow movement of termites between the
base and the bait matrix.
[0082] As best seen in Figs. 1 and 6, the cartridge 51 may
optionally comprise a cover 101 adapted for releasable securement to the
aggregation member 61 and/or the cartridge holder 65, and more suitably to
the peripheral side wall 95 of the tray portion 91 of the cartridge holder to
define an interior space of the cartridge in which the aggregation member and
bait matrix 63 are disposed so as to reduce their exposure to air and other
environmental conditions. It is understood, however, that the cover 101 may
be omitted from the cartridge 51 without departing from the scope of this
invention.
[0083] With reference again to Figs. 1 and 2, in a storage
configuration of the termite station 21 the cartridge 51 is disposed within
the
interior space 33 of the container 23 with the outer surfaces of the closed
ends 75 of the cartridge holder cups 73 facing the inner surface 37 of the
base panel 25 such that the cartridge cup portion sockets 81 receive the base
panel spacing members 49 to position the cartridge within the container. The
cover 101 of the cartridge 51 thus faces the lid 31 of the container 23 in
this
configuration with the lid in its closed position. To mount the termite
station
21 on a desired mounting surface M, the container lid 31 is moved to its open
position to provide access to the interior space 33 of the container 23 and
the
cartridge 51 is removed from the container. With the lid 31 open and the
cartridge 51 removed as illustrated in Fig. 10, the outer surface 35 of the
base
panel 25 is placed against the mounting surface M and suitable fasteners 43
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are used (i.e., extending through the base panel openings 39) to secure the
base panel (and hence the container 23) on the mounting surface. If the
cartridge 51 is to be further stored in the storage configuration of the
termite
station 21, it is simply placed back into the container 23 in the prescribed
orientation and the lid 31 is secured back in its closed position.
[0084] To use the termite station 21 for monitoring and/or
treating against termite infestation, the lid 31 is opened and the cartridge
51 is
removed from the container 23. The cartridge cover 101 (if present) is
removed from the cartridge 51 to ex pose the aggregation member 61 and
bait matrix tablets 69. The cartridge 51 is re-inserted, open end first, into
the
container 23 so that the aggregation member 61 now faces the base panel 25
and is otherwise spaced from the base panel by the standoff elements 99
(broadly, spacing structure) and the bait matrix tablets 69 are spaced from
the
base panel by spacing elements 49 as illustrated in Fig. 9. The lid 31 is then
secured in its closed position to fully enclose the cartridge 51 in the
container
23, thereby defining the operating configuration of the termite station 21.
The
aggregation member 61 (e.g., the heat-treated wood block 67 in the illustrated
embodiment), bait matrix 63 (e.g., the bait matrix tablets 69) and cartridge
holder 65 are sized and configured relative to each other such that the
aggregation member is nearer to the base panel 25 than the bait matrix and is
also nearer both laterally and longitudinally to the peripheral openings 47
formed in the end and side panels 27, 29 than the bait matrix in the operating
configuration of the termite station.
[0085] In operation, with the termite station 21 configured in its
operating configuration, as termites approach the base panel 25 from outside
the container 23, either from behind the base panel or from the sides of the
container, they quickly enter through the openings 39 formed in the base
panel or through the peripheral openings 47 formed in the end and/or side
panels 27, 29 where the corresponding access panels removed. The
placement and arrangement of the aggregation member 61 relative to the bait
matrix 63 (i.e., nearer to the base panel 25, end panels 27 and side panels 29
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than the bait matrix) results in the termites first encountering the
aggregation
member after entering the interior space 33 of the container. Where the
aggregation member 61 is a non-physical attractant, such as the previously
described heat-treated wood block 67, the termites may even be lured or
drawn by the aggregation member into the termite station 21. The termites,
induced by the aggregation member 61 to forage further within the container
23, ultimately discover and are induced to consume the bait matrix 63.
[0086] Where the bait matrix 63 is free from toxicant and is
used instead for monitoring, the termites leave visual evidence of attacking
the bait matrix, such as exploratory tunnels built by termites as they consume
the bait material so that signs of termite infestation are left on the surface
of
the material, or mud tubing constructed across the surface of the material or
into the cup portion of the cartridge holder. By adding toxicant to the bait
matrix 63, foraging termites ingest the toxicant-containing bait and return
portions of the bait to the nest through the pre-existing network of
passageways, thereby effectively treating against the infestation.
[0087] It is expected that over time the need to replace to the
cartridge 51 will arise, such as following long periods of non-infestation and
exposure to environmental conditions, or following prolonged periods of
infestation in which a substantial amount of the bait matrix 63 (e.g., the
tablets
69 of the illustrated embodiment) is consumed. The cartridge 51 may be
replaced by opening the lid 31, removing the old cartridge (e.g., as a single
unit) and inserting a new one that includes a new aggregation member 61 and
new tablets 69. Alternatively, if a new aggregation member 61 is not needed,
just the bait matrix 63 (e.g., the tablets 69) may be replaced in the old
cartridge 51 and the old cartridge reinserted back into the container 23.
Because the aggregation member 61, bait matrix 63 and holder 65 are held in
assembly as a single unit, the entire cartridge 51 is readily replaced without
having to reach into the termite station 21, i.e., only the cup portion 71 of
the
holder 65 need be grasped and pulled outward to remove the cartridge from
the container 23.
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[0088] While in the illustrated embodiments of Figs. 1-15B the
termite station is in the form of an above-ground termite station, it is
understood that the aggregation member comprising the wood heat-treated at
elevated temperatures as described herein may be used in an in-ground, or
subterranean termite stations. Subterranean termite stations, or other
subterranean insect (e.g., ant) stations, typically comprise a station housing
that seats within a cavity in the ground and has openings therein to permit
termites (or other insects) into the housing for subsequent treatment. One
example of a suitable subterranean termite station is illustrated and
described
in co-assigned U.S. Patent No. 7,086,196 entitled Pest Control Device And
Method, issued August 8, 2006, the entire disclosure of which is incorporated
herein by reference to the extent it is consistent herewith. It is understood,
however, that other suitable subterranean termite stations or other insect
treatment stations may be used without departing from the scope of this
invention.
[0089] With particular reference to Figs. 16 and 17, one
suitable subterranean termite station 510 includes a substantially hollow
housing 512 having an annular side wall 514, a top surface 516 and a bottom
surface 518 defining an interior volume 520. A portion of the top surface 16
of
the housing 512 is open exposing the interior volume 520. The station 10
receives one or more of an aggregation base 522, a monitoring container 524
and/or a bait container 525 (not shown but described below with reference to
Fig. 20) within the interior volume 520 of the housing 12.
[0090] A cap 528 is removably received on the top surface 516
to close the housing 512. The cap 528 is removably secured to the top
surface 516 of the housing 512. In one embodiment, the cap 528 has a pair
of tabs 530 that extend into slots 532 in the top surface 516 of the housing
512. The cap 528 is then rotated either counter clockwise or clockwise to
engage the cap 528. The tabs include a chamfer 534 along a leading edge
536 of the tab 530. As the cap 528 rotates into position, the chamfer 534
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helps guide the tab 530 into position within the slot 532. Other suitable
means for securing the cap 528 to the top surface 516 may be used.
[0091] Preferably, the housing 512 is formed from a durable,
corrosion resistant material, as for example, an acrylic or high strength
plastic.
Although shown as having a generally cylindrical shape, the housing 512 may
be any other suitable shape, such as rectangular. Preferably, the station 510
has a maximum height of less than about 18 inches (457 mm) and maximum
diameter or width of less than about 12 inches (305 mm), and more preferably
the station has a maximum height of less than about 9 inches (229 mm) and
maximum width of less than about 4 inches (102 mm).
[0092] The station 510 includes at least one opening 537
passing through the side wall 514 to permit the ingress and egress of termites
into and out of the interior volume 520 of station. Preferably, the side wall
514
has several vertical elongated openings 537 therein extending substantially
the entire length of the side wall. As used herewith, vertical is used in
reference to the preferred orientation of the station 510 with the top surface
516 facing in an upward direction. It is contemplated however, that other
shapes and orientations for the openings may be used. For example, the
openings may be horizontal elongated openings, or may be circular openings
randomly placed or formed in a repeating pattern. Additionally, there may be
openings 537 in the bottom surface 518 leading to the interior volume 520. In
an alternate version, the openings 537 are formed only in a lower portion 538
of the side wall 514 of the housing 512 such that an upper portion 539 of the
side wall 514 near the top surface 516 of the housing 512 is imperforate.
[0093] In use, the station 510 is at least partially received
within a cavity accessible to termites, while still being accessible above
ground by a user. The cavity may be a subterranean cavity, or may be a
cavity within a wall or other framework of a building or other above ground
structure. The cavity may be formed in the soil, or the cavity may be formed
in a paving material, such as concrete or asphalt, with soil beneath the
paving
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material. Preferably, the station 510 is substantially entirely received
within
the cavity such that only the top surface 516 and cap 528 are accessible from
above ground. However, in some situations, the station 510 may be nearly
entirely on top of the ground, such that the cavity is very shallow.
[0094] In one embodiment, as shown in Fig. 17, the
aggregation base 522 is received within the interior volume 520 of the housing
512 such that it is positioned adjacent the lower portion 538 of the side wall
514 so that the elongate openings 537 expose the aggregation base 522 to
the subterranean cavity. The monitoring container 524 or the bait container
525 is then received within the interior volume 520 of the housing so as to be
received adjacent to the aggregation base 522. It is also contemplated that
the aggregation base may be formed as a tube and the replaceable
monitoring container 524 or bait container 525 configured to be received
within the hollow interior of the tube.
[0095] Alternately, the aggregation base 522 is received
directly within the cavity. For example, when the aggregation base 522 is to
be used in a more durable environment where there is little possibility that
sidewalls of the cavity will collapse around the aggregation base 522, such
as,
for example, in paving material, the aggregation base 522 can be placed
directly into the cavity. The monitoring container 524 or the bait container
525
then may be positioned in the cavity adjacent to, and preferably directly
above, the aggregation base 522. In such an embodiment, there is no need
for a station to receive the aggregation base 522 and the containers 524, 525.
A suitable cap, designs of which are known in the art, would then be placed
over the cavity to secure the aggregation base 522 and containers 524 or 525
within the cavity. However, in the above embodiments, the aggregation base
522 is located in the cavity or station 510 in a substantially stationary
manner
so that there is minimal disturbance to the aggregation site and the termites
while the containers 524 or 525 are being inspected, removed and/or
replaced.
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[0096] Fig. 18 illustrates an embodiment of the aggregation
base 522. In the illustrated example, the aggregation base is formed in a
generally cylindrical shape such that an outer surface 540 of the aggregation
base faces the interior of the sidewall 514 of the station 510 or cavity when
placed in service. Other versions of the aggregation base may have different
geometric shapes suitable for use depending on the cavity into which the
base is received. In an embodiment of the aggregation base 522 to be
received within the interior volume 520 of the station 510, it is preferable
that
the aggregation base 522 have a shape similar to the shape of the housing
512 with a width slightly less than an inner width of the housing 512 so that
the aggregation base 522 may be removably received in a snug fitting
relationship within the housing 512. Preferably, the aggregation base 522 has
a void 542 substantially centrally located within the aggregation base 522
which is suitable for an aggregation site for termites. The aggregation base
522 includes channels 544 passing through the aggregation base 522 from
the outer surface 540 inward to the void 542. Preferably, the channels 544
guide the termites from the outer surface 540 to the aggregation site in the
void 542 of the aggregation base 522. Preferably, the aggregation base 522
is made from a cellulosic material attractive to termites, such as wood.
[0097] Alternately, the aggregation base 522 may be made of
plastic or other suitable material and filled with cellulosic material, such
as
paper, cardboard, compressed tablets, or other suitable feeding material and
may have holes providing access to the feeding material. In such a version,
the aggregation base 522 may be similar in construction to the container 524.
Additionally, the aggregation base may be made from a foam material. In
some of these embodiments, the aggregation base may not have a void
space free of material, but the base is still preferably configured so that
termites feeding on the aggregation base or material within the aggregation
base will form an aggregation site within the base.
[0098] Referring now to Fig. 19, the monitoring container 524
comprises a cup 550. The cup 550 may have an accompanying lid 552. As
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illustrated, the cup 550 has a bottom surface 554 opposite the lid 552 so that
the monitoring container 524 is configured as a closed cylinder defining an
interior chamber 553 to complement the configuration of the housing 512.
The bottom surface 554 is described as the surface adjacent the aggregation
base 522 when the monitoring container 524 is placed in the station 510 in an
operational fashion, and for convenience, the lid 552 comprises the opposite
surface. However, it is contemplated that the monitoring container 524 may
also be inserted into the station 510 with the lid 552 adjacent the
aggregation
base 522. An outer width of the cup 550 is slightly less than an inner width
of
the housing 512 (Fig. 16) so that the cup may be removably received within
the housing. Preferably, the container 524 is made of plastic. Referring to
now Fig. 20, the bait container 525 preferably is of construction similar to
that
of the monitoring container 524 and corresponding parts are indicated by the
same reference numerals.
[0099] Referring to both Figs. 19 and 20, a suitable material
such as a monitoring medium 555 (shown in Fig. 19) that is attractive to
termites may be received within the chamber 553 of the monitoring container
524. A suitable material such as bait 557 which is both attractive and toxic
to
termites may be received within the chamber 553 of the bait container 525.
The monitoring medium 555 and the bait 557 preferably are in the form of
tablets that are easily insertable into the chamber 553. Use of the monitoring
medium 555 and the bait 557 will be more fully discussed below.
[00100] Preferably, the combined length of one container 524
or 525 and the aggregation base 522 is less than the length of the housing
512 so that the container 524 or 525 can be received within the housing 512
in a manner which will not interfere with placement of the cap 528 to cover
the
top surface 516 of the housing 512. Preferably, for reasons which will be
more fully discussed below, the lid 552 and/or the cup 550 are transparent (or
at least partially transparent).
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[00101] As shown in Fig. 21, the cup 550 has at least one
opening 566 in the bottom surface 554 facing the aggregation base 522. The
opening 66 in the bottom surface 554 leads to the interior of the cup 550 when
the container 524 or 525 is received in an operational position within the
housing 512 thereby allowing the termites to move from the aggregation base
522 too within the interior of the cup. Multiple openings 566 are preferred in
the bottom surface, but a single opening design is also contemplated. For
example, the cup 550 may have a single opening 566 with a slightly irregular
shape (e.g., cloverleaf shape). Additionally, it is contemplated in some
versions that the cup 550 may have holes in the sidewalls thereof. The
termites must have access to the openings 566 in the cup 550 from the
aggregation base 522. In one embodiment, small legs 568 on the bottom
surface 554 of the cup 550 space the cup from the aggregation base 522 to
provide a gap for termite exploration.
[0100] The monitoring container 524 is configured to be
replaceably received adjacent the aggregation base 522 (see, e.g., Fig.
17), such that the monitoring container 524 may be removed, inspected
and/or replaced without disturbing the aggregation base 522, thereby
preserving any aggregation site formed by the termites in the
aggregation base 522, such as within the void 542. Similarly, the bait
container 525 is configured to be replaceably received adjacent the
aggregation base 522, such that during use, either the monitoring
container 524 or the bait container 525 is positioned adjacent the
aggregation base.
[0101] The lid 552 of the containers 524, 525 also may
have at least one opening 570 (see Fig. 23), the at least one opening
allowing the termites to move into and out of the container through the lid
552 of the container. Additionally, the openings 570 prevent the
container 524, 525 from floating if the station 510 or cavity fills with
water. Also, if the monitoring medium 555 or bait 557 received within the
containers 524, 525 becomes water soaked and expands, the openings
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566, 570 provide room for expansion, yet keep the bait inside the
containers. Sides 572 of the cup 550 are preferably free of openings so
that the termites passing through the openings 537 in the housing 512
are driven down to the aggregation base 522 so that the initial
aggregation site is formed in the aggregation base. However, when the
cup 550 is used as a monitoring container 24, openings may also be
included in the sides.
[0102] The lid 552 is removably secured to the cup 550
using any suitable means. Referring to Fig. 22, in one embodiment, the
cup 550 has several recesses 559 near a top rim 558 thereof. Fig. 23
illustrates corresponding flanges 560 on the lid 552 that are received in
the recesses 559 to secure the lid 552 to the cup 550. Alternately, a
circular threaded portion (not shown) of the cup 550 extends upwardly,
and a complementary threaded base portion (not shown) of the lid 552 is
removably securable to the cup 550 by screw threads.
[0103] In operation, a cavity of appropriate dimensions
can be made in the soil or other structure for positioning of the station
510. Typically, the aggregation base 522 and monitoring container 524
are placed inside the station housing 512, and the station 510 is then
inserted or pressed into the cavity until the top surface 516 of the station
housing 512 is near the soil surface. However, in some instances, such
as when there is a known presence of or conditions conducive for
termites, it may be desirable to directly begin using the bait container 525
with the aggregation base 522 and not use a monitoring container 524.
Alternatively, the aggregation base 522 is placed directly into the cavity.
The container, either 524 or 525, is then placed into the cavity adjacent
the aggregation base 522. The description below will describe the
aggregation base 522 as being placed within the station 510, but it is
contemplated that the aggregation base may be placed adjacent to the
monitoring container 524 or bait container 525 without the use of a
station 510 as described above. Termites locate the station 510 and the
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aggregation base 522 as the result of their foraging in search of food
sources.
[0104] As termites approach the outside of the station
510, they quickly enter through the openings 537 and move inside to find
the aggregation base 522, which is a potential food source. The
openings 537 in the station encourage the termites to quickly pass
through the side wall 14 to the aggregation base 522. If the termites
enter through the openings 537 and contact the container 524 or 525
above the aggregation base 522, the imperforate sidewalls of the
container direct the termites down along the elongate openings 537 to
the aggregation base 522. The channels 544 encourage the termites to
enter the aggregation base 522 and begin to use the internal void 542
created by the base as an aggregation site. The void 542 creates a
stopping area in the center for aggregation. Once inside, they will move
toward the top of the aggregation base 522 and into the monitoring
container 524. Because only the monitoring container 524 is removed to
monitor for termite activity, the aggregation base 522 remains
undisturbed, thereby maintaining the void 542 of the aggregation base
522 and the aggregation site therein intact.
[0105] The station 510 can be inspected periodically for
evidence of termite infestation by visually examining the monitoring
container 524 for signs of infestation. Inspection of the station 510 can
be performed weekly, bi-weekly, monthly, etc. as needed or desired. An
inspection is performed by removing the cap 528 and visually inspecting
the chamber 553 of the monitoring container 524 or the aggregation
base 522 for termite attack. Because of the nature of termite attack
against a cellulosic material, such as the monitoring medium 555 or the
aggregation base 522, visible signs or evidence of such attack will
invariably be left on the monitors. This evidence can include, for
example, exploratory tunnels built by termites as they consume the
material in such a way that telltale signs of termite infestation are left on
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the surface of the material and/or mud tubing constructed over and
across the interior surface of the station housing 512 or monitoring
container 524. Such signs of infestation would be obvious to anyone
skilled in the art of termite damage detection. If termite attack is
discovered, the station 510 is baited by replacing the monitoring
container 524 with a bait container 525. Alternately, the monitoring
medium 555 can be removed and replaced with the bait 557. If no
termite attack is discovered, the monitoring container 524 is returned to
the station 510. The cap 528 is replaced and the station 510 is
inspected again after the appropriate interval.
[0106] Termites consuming the aggregation base 522 will
discover and transition to feeding upon the nearby monitoring medium
555 in the monitoring container 524. This can be for one or more
reasons. If the monitoring medium 555 is of a consistency more
preferred by termites than the aggregation base 522, then termites may
cease to consume the aggregation base 522 and transition to consuming
the monitoring medium 555 before the entire aggregation base 522 is
consumed. If termites continue to consume the aggregation base 522,
the termites will still transition in the normal process of termite foraging
to
consuming the monitoring medium 555 when the aggregation base 522
is entirely consumed. Because the monitoring medium 555 is nearby
and is of a nature preferably consumed by termites, they invariably begin
consuming the monitoring medium.
[0107] Once termites have been discovered attacking the
monitoring medium 555 or aggregation base 522, the station 510 is
baited with the toxicant containing bait 557. Preferably, the monitoring
container 524 is removed and replaced with the bait 557 in container
525. The toxicant-containing bait may be in the form of purified cellulose
toxicant delivery tablets. One suitable termite bait composition is
described in co-assigned U.S. Patent No. 6,416,752 entitled "Termite
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Bait Composition and Method", the disclosure of which is incorporated
herein in its entirety by reference.
[0108] The toxicant in the bait 57 is preferably of the
delayed-action type, or an insect growth regulator, pathogen or metabolic
inhibitor. Preferably, it comprises a nontoxic bait composition to which
the pesticide toxicant is added. Any suitable termite pesticide
composition may be used in connection with the present invention. In
one embodiment, the bait is in the form of tablets. For example, in one
suitable embodiment, the bait 557 comprises at least one compressed
tablet having a mass of between about 10 grams (0.35 ounce) and about
45 grams (1.6 ounces), more preferably between about 25 grams (0.88
ounce) and about 40 grams (1.4 ounces), and even more preferably
about 35 grams (1.2 ounces).
[0109] The removal, inspection and/or replacement of the
containers 524, 525 within the housing 512 does not substantially disturb
the pre-existing network of access galleries or passageways previously
established between the termite colony or nest and the aggregation site
in the aggregation base 522 since the base is not displaced during
removal and substitution of the container 524, 525. Thus, the
disturbance of the aggregation site in the aggregation base 522 is
minimized, reducing the likelihood that the termites will abandon the
feeding site. Also, communication and access between the pesticide
containing container 525 and the termite colony is quickly established
upon substitution of the monitoring container 524 with the bait container
525. Foraging termites ingest the pesticide-containing bait 557 and also
return portions of the toxic bait to the nest through the pre-existing
network of passageways.
[0110] The station 510 is inspected at regular intervals
(e.g., every 15 to 120 days) to assess the extent of termite consumption
of the bait 557. When the bait 557 in the container 525 has been
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substantially consumed, more bait can be added by removing the lid 552
and inserting more bait in the container 525 or simply by replacing the
container with a fresh container. Thus, during normal inspection and/or
replacement of containers 524, 525, the aggregation base 522 is not
removed and disturbance to the aggregation site is minimized. It may be
necessary to periodically replace the aggregation base 522 (e.g., once a
year to freshen up the aggregation base 522). This however, is not
usually done while termites are actively feeding from the site.
[0111] In accordance with another embodiment of a method
for treating insects, and more suitably for treating subterranean insects and
even more suitably for treating subterranean termites, the heat-treated wood
described previously herein may be deployed in the station housing instead
of, or in addition to, the aggregation base 522. For example, in one
embodiment the aggregation base may be formed of the heat-treated wood
but otherwise constructed in the same manner as the aggregation base
illustrated in Figs. 16 and 17. In another embodiment, the aggregation base
522 may be formed of the heat-treated wood but deployed in the station
housing as mulch, powder, chips or other particulate form. In still another
embodiment, the aggregation base may be constructed in the same manner
as the aggregation base illustrated in Figs. 16 and 17 and may be need not
necessarily be formed from the heat-treated wood. In such an embodiment
heat-treated wood in the form of mulch, powder, chips or other particulate
form may additionally be placed in the station housing adjacent the
aggregation base.
[0112] In each of the above embodiments, the heat-treated
wood is suitably exposed to the moist environment (e.g., moist air, soil,
and/or
ground water) surrounding the station housing, such as by being directly
exposed to the environment surround the station housing, or by being placed
in a container that is suitably liquid permeable to permit exposure of the
heat-
treated wood to moisture in the environment surrounding the container. In
such an arrangement, upon exposure to sufficient moisture, a liquid extract
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containing one or more compositions of the heat-treated wood leaches from
the heat-treated wood out of the station housing and into the surrounding
soil.
The liquid extract thus broadly defines a liquid attractant and generally
forms
an attractant zone surrounding the station housing to further attract termites
to
the station housing.
[0113] In another embodiment of a method for monitoring
and/or controlling insects, and more suitably for monitoring and/or
controlling
insects and even more suitably for monitoring and/or controlling termites, a
heat treated wood extract is suitably generated from the heat-treated wood
and then deposited in an area to be monitored and controlled (e.g., into a
cavity where no station housing is used) for use in attracting and monitoring
termite activity, or deposited into the soil or other environment exterior of
the
station housing, and/or deposited into the station housing for subsequent
release into and absorption by the soil surrounding the station housing. As
used herein, the term "heat treated wood extract is intended to broadly refer
to
a liquid extract such as an aqueous extract or non-aqueous extract of the heat
treated wood, or a solid extract (such as in a solid, particulate or other
dried
form) of a liquid extract of the heat treated wood.
[0114] As one example of a particularly suitable embodiment,
the dried heat treated wood described above is subjected to a water
extraction to generate an aqueous heat treated wood extract. More suitably,
in accordance with one process for generating the aqueous extract, the dried,
heat treated wood, in particular form, is combined with a volume of water and
the mixture is heated, and more suitably brought to a boil for a time period
of
at least about 10 minutes, more suitably in the range of about 10 minutes to
about 120 minutes, and even more suitably in the range of about 30 minutes
to about 120 minutes. The mixture is then filtered to remove particulates,
leaving an aqueous heat-treated wood extract containing extractives from the
heat treated wood. It is contemplated that a liquid extract may be generated
other than in water to provide a non-aqueous heat treated wood extract
without departing from the scope of this invention. The liquid heat treated
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wood extract generated via extraction may be used as an attractant by itself
or in conjunction with an insect monitor and/or control system such as the
above-ground system of Figs. 1-1 5B or the subterranean system of Figs. 16
and 17 to facilitate attraction of insects, e.g., termites.
EXPERIMENT 2
[0115] In this experiment, an aqueous heat treated wood
extract of aspen wood heat-treated according to one suitable embodiment,
and filtered water, were evaluated to determine Reticulitermues flavipes
termite feeding preference between these samples.
[0116] The heat-treated wood was processed as follows to
generate the aqueous extract. The wood was cut to a common board
dimension, such as a standard 2x4 plank (i.e., cross section of about 38
millimeters (1.5 inches) by about 89 millimeters (3.5 inches)). The wood was
then placed within a kiln or high temperature/pressure vessel. The
temperature within the vessel was increased rapidly to about 100 degrees C
(212 degrees F) and held until the wood uniformly reached approximately
zero percent moisture content. The temperature was then steadily increased
to and maintained at about 185 degrees C (365 degrees F) for a period of
about 120 to 180 minutes. After drying, the temperature of the wood was
decreased to between about 80 degrees C (176 degrees F) and about 90
degrees C (194 degrees F). A steam spray was used during the cooling
period to reduce the temperature of the wood and to increase the moisture
content of the wood to between two percent and about ten percent. The
entire heating and cooling down process took approximately 36 hours to
complete.
[0117] The heat treated wood was ground by mechanical
process until the particulate size of the material was in the range of 1 to
250
microns. A measure amount equal to approximately one-third the volume of a
standard U.S. gallon liquid was then placed in filtered water and boiled for a
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period of 20 minutes. After boiling, the water/heat-treated wood mixture was
allowed to cool and then filtered to remove particulates from the mixture,
leaving the aqueous heat treated wood extract.
[0118] Whatman brand filter papers, Cat. No. 1001-150 (150
mm diameter) were soaked in the aqueous heat treated wood extract and
allowed to air dry. Additional filter papers were soaked in filtered water
(e.g.,
without heat treated wood extractives) and allowed to air dry. The dried
filter
papers were then placed about 12 inches apart on top of termite infested soil
inside an aquarium for a period of two weeks, during which time the aquarium
was visually inspected and termite activity observed. After two weeks, visual
observation revealed that the filter paper treated with the aqueous heat
treated wood extract was extensively fed upon and penetrated, while the filter
paper treated with filtered water had substantially less feeding activity and
in
some instances no feeding activity.
[0119] In one suitable embodiment of a method for monitoring
and/or controlling insect populations, and more suitably termite populations,
the aqueous heat treated wood extract (broadly, the liquid heat treated wood
extract and more broadly the heat treated wood extract) is delivered to the
station housing of a termite monitor and control system such as the system of
Figs. 1-15B, the system of Figs. 16 and 17 or another suitable system. For
example, for a subterranean system as illustrated in Figs. 16 and 17, with the
station housing already positioned within the cavity the aqueous heat treated
wood extract is poured down into the station housing so the extract runs out
of
the station housing via the openings therein and is dispersed into the soil
surrounding the station housing to create a zone of attractant exterior of and
surrounding the station housing. In other embodiments, the aggregation base
(and in some instances other components such as the monitoring container)
may already be loaded into the station housing at the time the aqueous heat
treated extract is poured into the housing.
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[0120] In another embodiment, the liquid heat treated wood
extract may be carried on or in a suitable carrier, such as by being soaked
into or coated on a substrate such as cardboard, paper, wood or other
suitable substrate, or contained within a suitable container (broadly, a
carrier)
that allows the solution to leak out therefrom. In such an embodiment the
carrier may be placed in the station housing of an above ground system (Figs.
1-15B) or subterranean system (Figs. 16 and 17) instead of, or in addition to,
the aggregation base. In another aspect, a substrate carrier to which the
liquid heat treated wood extract is added may be dried prior to loading the
substrate into the station housing.
[0121] In other embodiments, a liquid heat treated wood
extract may be subjected to de-solventization, such as without limitation
boiling down the extract, by freeze-drying, by vapor induced evaporation,
another suitable de-solventization process or any combination thereof to
generate a heat treated wood extract in solid form (i.e., a solid mass or a
particulate such as a powder or crystalline form). The heat treated wood
extract may then be placed into the station housing in the same manner as
the liquid heat treated wood extract and/or the particulate heat treated wood
described previously.
[0122] When introducing elements of the present invention or
the embodiment(s) thereof, the articles "a," "an," "the," and "said" are
intended
to mean that there are one or more of the elements. The terms "comprising,"
"including," and "having" are intended to be inclusive and mean that there may
be additional elements other than the listed elements.
[0123] As various changes could be made in the above
products and methods without departing from the scope of the invention, it is
intended that all matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative and not in a
limiting
sense.
