Abstract
For years the pest Management Professional
has relied on visual and manual inspections to locate insect
pest infestations. As building materials have improved,
the ability to locate pest problems has become more difficult
since building materials are often able to mask the existence
of pest infestation. Additionally, these improved building
materials have contributed to the pest problem by providing
a convenient food and nesting source.
Within the past five years, the Pest Management Industry
has become aware that IR thermography can aid in the detection
of pest infestation by detecting evidence of latent moisture
within structures. This paper discusses the use of thermal
imaging to detect thermal patterns associated with insect
infestation, verification of data and special challenges
associated with the inspection process.
History
Pest control has been around since before
mankind. Initially it was performed by our ancestors who,
living in trees or on the ground, continually groomed themselves
to be free from insect pests. Fundamentally, it was an
activity that relied upon sight. If you could see them
you could dispose of them. The evolution of pest control
continued in concert with the evolution of man. As the
eras moved forward and man evolved into modern man, the
activities of pest control also evolved, but not quite
at the same pace.
As evolution continued through the
stone and tool age, man soon realized the use of a club-like
implement or a
stone was preferable to the use of his hand or bare foot.
It’s a hard act to stomp on a scorpion without getting
stung.
The club evolved to the use of tools.
With the abundance of 
pests in man’s world, it
became a profession, hopefully operated by men who were
more skilled and more
knowledgeable in the art of locating and disposing of the
unwanted pests than our ancestors.
The profession expanded and as man became less tolerant
of different types of pests, the skills of the pest control
professional also needed to advance.
Fortunately, the use of chemicals became
one of the answers. The killing of pests still relied in
part on seeing them,
but once seen, the use of chemicals was then the answer.
Industry brought forth the use of a wide variety of various
chemistries that had significant success in the killing
of those blasted pests, but
unfortunately, some of these
chemicals, like DDT, produced unwanted results. Mutations
and the disintegration of some of the vital DNA chains
were seen as well as gradual pest resistance to various
chemicals.
As we moved into the 70’s, the pest
population again began to expand. The pest professional
however, still relied
upon his sight to locate pest infestations. Timeworn basic
tools – a prod, now in the form of a screwdriver
and a portable light – the flashlight was used to
see possible signs of insect pest problems. The pest professional
still relied on his basic Rule of Thumb - if he could see ‘em,
he could kill ‘em.
Modern construction materials as well
as better construction techniques have provided new forms
of harborage and new
food sources for the insect pests. The use of slab
construction has in one respect made the home stronger
and more durable
while on the other hand it has helped in hiding entry
points that the pests use. Plasterboard or gypsum
board has replaced lathe and plaster, providing uniform
strength and ease of installation, but unfortunately it
offers a
great food source for the
cellulose eaters such
as termites. A good carpenter will, to the naked eye,
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Termite
alate.
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Termite swarm. |
create
tight joints and flush fittings, however, hidden behind
that paint and stucco are tiny openings perhaps only 1/16” in
diameter. These small openings can permit the entry of
tiny termite alates that can mature into a termite queen
capable of fostering millions of other termites or permit
the entry of other insect pests such as carpenter ants.
Some pests such as carpenter bees need no man-made or opening
created by shrinkage, they create their own entryway by
chewing their way into a structure.
The insect pests live virtually hidden from view and flourish,
happily munching away, almost always only to be discovered
when they leave a sign of their presence. Perhaps that
sign is in the form of fecal droppings, called frass, or
perhaps it is only found when the bubbling paint becomes
obvious or even more obviously when the floor or ceiling
collapses. These types of occurrences are obviously too
late to prevent the damage, but provide sufficient evidence
for immediate pest control action and possible lawsuits.
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Above are two views of the Le Dale
Hotel and Bar ceiling that collapsed from Formosan
termite
damage.
~ Courtesy Jack
Leonard – New
Orleans. |
Use of Thermal Imaging as a Tool
About six or seven years ago, a
gentlemen involved in the pest control industry asked
a vendor who was promoting
the use of an IR camera at a trade show if he could find
termites with the camera. The gentleman asking the question
was Jack Leonard, who was employed by the only publicly
funded pest control agency – the New Orleans Mosquito
and Termite Control Board (NOMTCB). The vendor was Bob
Melia, who was a prime mover in the US Coast Guard’s employment
of thermal imaging cameras. And so the saga began. They
began testing cameras and various lenses and soon the duo
noticed that when they imaged the interior of buildings
in New Orleans and found anomalous cooling, there was a
correlation between the presence of moisture and the possible
presence of insect pests – in their case Formosan
termites. They also discovered that when they noted anomalies
on wall or wood structures, in many cases the anomalies
represented subsurface defects that had a high correlation
with damage that had been or was being done within the
wood structures, again by termites. In both cases the anomalies
were not visible to the naked eye.
With positive result after positive result, and being
in a region infested with the very destructive Formosan
termite, the use of the IR thermal imaging camera became
a key tool in Operation Full Stop (1998 to present), a
USDA and US Congress mandated project aimed at containing
and treating the Formosan Termite infestation in the Historic
New Orleans French Quarter. Today, an IR thermal imaging
camera is a tool to be used whenever the NOMTCB does termite
pest inspections in New Orleans, and Jack Leonard, though
retired, has perhaps more experience than any other professional
in termite detection using IR cameras.
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The use of the IR camera as a tool in the pest control
industry is perhaps somewhat different than, for instance,
using the thermal imaging camera for the inspection
of electrical circuitry, the inspection of refractories
or for the inspection of operating machinery or equipment.
In most of these instances, the thermal emissions are
of a high temperature and the IR imagery is readily
obvious. |
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~ Images courtesy
of Jeresy Infrared Consultants. |
The use of the IR camera as a tool in the pest control
industry is perhaps somewhat different than, for instance,
using the thermal imaging camera for the inspection of
electrical circuitry, the inspection of refractories or
for the inspection of operating machinery or equipment.
In most of these instances, the thermal emissions are of
a high temperature and the IR imagery is readily obvious.
On the other hand, inspections utilizing
IR imagery in pest control consists almost entirely of
low or near ambient
temperature emissions with sometimes very subtle changes
in imagery. It is not only the
skilled eye of the thermographer,
but also an understanding of what the attendant situation
might be that aides the thermographer in
making proper interpretations and analysis of the IR
imagery. Understanding and having knowledge of the
primary factors that are associated with some insect pest
problems is an absolute requirement. Knowing and understanding
other factors that are associated with other pest
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Termite mud tube
on pier blocks.
~ Orlando,FL
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problems
such as seasonal and regional nuances also leads
to the
proper interpretation and analysis of the imagery.
Any thermographer providing services in pest control
must be aware that in a vast majority of
the cases, the anomalies may be very, very small
and may be easily overlooked. A typical termite mud tube
might be less than 1/4 of an inch wide and may be
on
the inside of a gypsum wall or hidden in a small
crack in brickwork or located inside a concrete block.
In
addition,
an active termite mud tube might contain less than
10% in moisture. Obviously, difficult to see and easily
overlooked
but a miss, when it comes to pest control, can result
in hundreds, thousands or tens of thousands of dollars
worth of damage. On the other hand, locating an infestation
of termites in its early stages might save thousands
or even tens of thousands of dollars worth of damage
as many a lawsuit will attest. In addition, locating
toxic black and other molds may forestall sickness
and even death.
As an example, let’s assume
that we are inspecting a house for insect pests. Assume
the house is air conditioned
with reverse cycle heating, has wood flooring, is fully
insulated, and is in a tropical climate alongside a stream
feeding into a nearby lake. The house has a 15-year-old
tile roof and is surrounded by excellent landscaping with
lots of shade trees providing harborage for squirrels,
birds and the usual array of neighboring possums, raccoons,
rats and mice which the homeowners dearly love; well, maybe
not the possums, rats and mice. The house has a brick and
stucco face over highly efficient EIFS (foamed sheet) insulation
and has a basement, a few crawl spaces under the porches
and an attic. Really a beautiful house.
Welcome to the pest inspectors nightmare.
Let us further assume that when
we arrive we have good conditions, not perfect, but good;
it’s 90ºF
outside and with the A/C on it’s 78ºF inside.
Cranking down the air will give us better conditions, so
we set the temperature to 65ºF as we go about our
business. Now we are ready to begin.
Initially we will make a sketch of the layout of the house,
make some approximate dimensional notes, note the orientation
to the compass, move to the outside, check the sun and
wind conditions and take some digital pictures.
The typical inspector in the pest control industry of
today is typically armed with advanced tools of his trade – a
flashlight and a screwdriver. With these technical tools,
today’s pest inspector looks for visual signs of
a pest infestation.
On the exterior of the house, the
pest inspector is typically looking for things such as
peeling paint, signs of cracking,
signs of moisture, soil against the side of the house and
other signs that might signal conducive areas for pest
infestation or other signs of abnormalities. Unfortunately,
the average pest inspector might miss more than he finds.
It may be as simple as not being able to see that problem
up into the eaves because it’s too high to visualize
or that it is too well hidden from the naked eye or perhaps
when he is doing his inspection, he left the motor running
in his truck, simply making sure that his customer, the
seller’s real estate agent, is kept happy by a clean
inspection. (No inference intended.)
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Crawl space area visually
showing presence of termite mud tubes both of active
and inactive nature.
Courtesy – Advance Tech
Pest Management, Clermont, FL. |
In the interior of the house, the pest inspector again
will be looking for similar signs. He will also look for
insect wings, frass (fecal droppings, aka poop) and will
do a lot of tapping with the butt end of the screwdriver
in likely areas such as door jams, sill plates, widow sills,
floor boards, etc. always hoping to hear a hollow sound
that might signal deterioration. Year after year, the pest
inspectors are called to sites that have had swarming termites
and are unable to find the exact location of the infestation.
If there is fraz or pellet evidence, some inspectors can
tell what type of termite, borer or even what type of ant
has caused the problem. If any of these elements are located,
the pest inspector, now alert to the possibility of a payday,
makes every effort to locate the pest infestation itself.
If he is able to do that, he will most probably cinch the
deal and ring the cash register. Knowing what types of
bugs are in the area and having a gift of the gab, he may
either end up selling a fumigation job or miss getting
the job because he could not convince the homeowner of
the location of the pesky critters.
Detection of Thermal Patterns Associated with Pest Infestation
The IR camera can best be classified for the pest management
professional as a gross overview inspection tool. As in
most thermal imaging inspections, the IR camera is but
one tool in the inspection process. Thermal imaging permits
a skilled operator to rapidly inspect a site. At the outset,
there are two (2) elements a trained inspector will be
looking for: 1) areas exhibiting anomalous cooling behavior
usually associated with the presence of moisture, and 2)
the presence of subsurface defects. In addition, thermal
imaging can play a significant role in other phases of
pest inspection such as resultant treatment or remediation.
As mentioned above, one of the major signs of a possible
pest infestation is latent moisture. That moisture, in
the case of a pest infestation, is a critical element needed
to support the life of the insect pest. Some insect pests
can live on as little as 2-5% moisture, while others, especially
where there is an above ground colony, may require significantly
more. Therefore, one of the primary objectives in any thermal
inspection process is to locate evidence of the thermal
patterns that exhibit anomalous cooling which in many cases
indicates the presence of latent moisture.
Moisture
Remember the house we are inspecting. It is near a lake
and has a nearby stream. The climate is warm. The surrounding
area is obviously moist. Prime area for all sorts of critters.
The locations of these signs on the outside or underneath
the structure may be anywhere. Any and all locations need
to be charted and checked. Additionally, the presence of
moisture on the outside may or may not evidence itself
on the inside of the
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Water and termite
damage at windowsill with
EIFS insulation (EIFS removed) |
Active termite tubes on cement blocks.
Courtesy
Jack Leonard- New Orleans. |
structure. Beginning with each side of the building and
taking into account the position of the sun and the wind
factors, close inspection of the areas in contact with
the ground, behind the plant beds and other areas where
plants and/or trees touch the structure, the brickwork
and the areas where the stucco covers the EIFS and in the
cracks and voids of the tile roof are prime areas of focus.
The anomalies may
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Courtesy – Advance Tech
Pest Management,
Clermont, FL.
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be minute in nature, slight evidence
of dirt in the cracks of the brickwork, minor shading
in the stucco areas, around window sills, doorways and
door
entryways. Remember it was said that the nightmare was
beginning. A good knowledge of historical pest problems
enables the pest thermographer to know that stucco over
EIFS is prone to holding moisture and can act as a harborage
for insect pests. So if the presence of EIFS or similar
products is known, extra diligence is required in the
inspection process.
All porches, verandas, lattices, sole and sill plates
and even the outside fence and fence posts need to be scanned.
The crawlspace will need to be entered and all the brickwork,
piers, beams, pilings and even the rubble stone supports
need to be examined and scanned.
The following are examples of some recent images that
exemplify some issues to be looked for:
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Damage
in eaves area – Orlando
FL.
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Anomalous cooling
in exterior wall area,
no gutters to permit runoff
- Orlando, FL. |
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Anomalous cooling in wall area. Orlando, FL
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The
presence of moisture on the inside
may also be anywhere, the basement, the crawlspace, baseboards,
walls, ceilings, under floor tile or marble tile, under
the showers or the bathtub, in the laundry room or in the
attic. The complete structure requires scanning, all closets,
cabinet areas, laundry and utility areas, including electrical
panels, for signs of anomalies. Once an anomaly is located,
notation should be made and documented not only with IR
images but also with digital images.
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Digital, grayscale
and colorized images of wall area in house with termite
activity behind
wall.
– Jack Leonard New Orleans |
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Digital, grayscale and colorized images
of floor area in house with termite activity.
– Jack
Leonard New Orleans. |
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Digital, grayscale and colorized image
of wall area with active termite activity.
– Jack
Leonard New Orleans. |
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Digital, grayscale and colorized image
of wall area with active termite activity.
– Michael
Potter, PhD. Lex.,KY.
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Grayscale and colorized images of basement
box header with termite activity.
– Michael
Potter, PhD. Lex.,KY.
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It is imperative to understand and
learn the basic patterns of moisture that may be indicative
of an insect pest problem.
As stated above, termite mud tubes are commonly less than
1/4 inch in width and may be hidden within a wall structure
making it very difficult to spot mud tube activity. In
addition, mud tubes are the highways used by the subterranean
termite. Since that variety usually lives in the ground,
they must find some means to enter into any given structure.
That entry point may be where a pipe enters the building,
where soil is against the side of a structure providing
access to the side of a structure above its slab or even
from a tree leaning up or growing against a structure providing
a convenient above ground entry point. Again, the mud tubes
provide the highway from the ground and offer the opportunity
to discover their presence, but once located, you need
to then determine where that highway is going and what
the extent of infestation is. The highway is usually going
toward a source of cellulose – the main dietary requirement
of any termite. Wood framing, sill plates, beams, wall
studs, cabinetry and even the paper on the backside of
the gypsum board all can fill the dietary needs of the
termite. A typical house could provide sufficient food
to support millions of termites for many years.
Usually, the mud tubes of termites are two-laned highways.
The trailers are the termites carrying the food from the
feeding location to the colony in the ground that then
return to the feeding area passing each other as they go.
They carry the moisture from the ground up into the tubes
to keep them moist. Occasionally, the termites are lucky
enough to locate a source of moisture within the structure
that is continuous and sufficient to support the needs
of a colony. The termites may then set up an above ground
colony that is very close to their food source. And assuming
that the structure is heated or in a warm climate, it can
provide optimal conditions on a year-round basis to support
a termite infestation.
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Digital,
grayscale and colorized images of inside basement
wall area with termite activity.
– Michael
Potter, PhD. Lex.,KY.
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Grayscale
and colorized images of 2 separate wall areas in
house
with unknown anomaly at left
and hidden termite carton nest at right.
– Michael
Potter, PhD. Lex.,KY.
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Mold
Moisture may also be an indicator
of the presence of another problem – fungi or mold.
Indoor mold has been characterized in recent years as
the indoor killer. It is currently considered
the big threat to buildings and their occupants and is
considered to be a responsible factor in sick building
syndrome. In some states, like Florida, mold falls within
the pest control category. Not all molds are dangerous,
however all molds should be treated with the same respect
due to potential health issues. Any presence of latent
moisture both on surfaces and in subsurfaces discovered
during an IR inspection are important indicators that need
to be thoroughly investigated.
The following images are examples of visible mold as well
as IR images of locations were mold was discovered after
further examination of an active moist area.
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Stachybotrys chartarum
mold in bathroom wall.
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Mold in HVAC ductwork. |
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Active
mold in crawl space located in Miami, FL.
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Active
moisture area in beam and ceiling where active mold
growth was revealed – Miami, FL
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Much more can be said about the use of thermography in
the inspection, detection and remediation of mold. Suffice
it to say, IR thermal imaging is an important resource
tool for the detection as well as the remediation of mold
and is the subject of many present discussions.
Subsurface Defects
| As mentioned earlier, the presence of subsurface
defects may be an indication of the presence of insect
pests. A skilled inspector will need to exclude or
factor out other benign sources, such as IR emissisivity
variations, reflections, surface markings or blemishes
of the surface being observed. Insect pests like drywood
termites, wood borers, carpenter ants and certain bees,
are all wood destroying insects that eat or excavate
the softer part of the wood or cellulose structure,
sometimes leaving a perfectly good looking exterior
shell. Sometimes, the structural integrity of the structure
has been compromised without any visual signs. |
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Digital image of exposed interior stud |
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| Use of the thermal imaging camera can in many cases
locate these problems by showing subsurface defects.
However, it takes not only the skill of a thermographer,
but also an intense knowledge of the possible insect
pests normally found in the local area as well as an
understanding of the type of damage each different
pest can cause. Only with that knowledge, can a proper
inspection and image interpretation be accomplished. |
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Colorized image
of subsurface
defect in interior stud |
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Subsurface
defects shown in both images using active thermography – Orlando,
FL.
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As an example, drywood termites habitually
infest a piece of wood and create galleries within that
wood structure. These galleries are simply tunnel-like
voids that have been eaten out by the termites or other
woodborers. The termites may remain hidden for years. Generally,
they create a kick-hole that is used to expel their droppings
(frass). If this frass is dropped behind or within a wall
structure, it may not be seen. If however, a swarm takes
place, and reproductive termites take to the air in search
of finding a new nesting area, their presence may be noted
and then the search for the termite gallery will begin.
A drywood infestation may be in any piece of wood; in
a door jam, in an attic, or even in the wood stud within
a wall structure. In order to locate them, the insect pest
thermographer may need to resort to active thermography
to determine their presence. Active thermography may consist
of actively heating or even cooling structural areas while
being viewed through the IR camera. Heating may be accomplished
by using the thermal wave technique, which is an extension
of basic heat conduction theory. The surface of the area
is briefly and uniformly heated by a brief flash from a
flash lamp
array. If the area has no gallery, the heat will diffuse
fairly uniformly. Similarly, cooling agents may be utilized
to accomplish similar results.
If, on the other hand, there are termite or other pest
galleries present, the flow of heat into the structure
will be obstructed and the rate of cooling at the surface
immediately above the gallery would be retarded. Cooling
agents can also be used. If the inspector is able to locate
a kick hole, he then has the ability to inject a short
blast of cooled compressed air, which when released into
the hole, will invade the gallery and the cooling effect
will become evident on the thermal imager. Active thermography
is in some cases, the only way in which the insect pest
infestation will be fully located. Above are several images
showing the results of active thermography.
Additional Uses of the Thermal Imager in
Pest Management
From time to time, during the process of performing a
pest inspection, the pest thermographer will undoubtedly
encounter many different situations that can be of benefit
to his client. Rodent and other small animal nests within
walls, crawl spaces or in attics are an additional problem.
The thermal imager will be of great assistance in locating
those warm blooded critters making nests in the attic,
in the crawl spaces or even inside walls. Care needs to
be taken when active nests are located. A startled rodent
can cause serious problems for a thermographer who has
a fear of rodents or who is suddenly surprised. Safety
of balance, especially when in tight crawl spaces, in attics
or on ladders is a must.
In addition, occasionally, there
may be a strong odor coming from the inside of walls,
attics or crawl spaces.
Don’t be surprised to find dead animals with the
uses of your thermal imager. Simply wear appropriate clothing
and protective gear when removing the carcass.
| Since part of the pest
detection inspection process also includes scanning
such things as the electrical panels and plumbing areas,
it will not be unusual to locate electrical problems
like undersized wires, defective circuit breakers or
loose connections or leaks not only from plumbing problems
but from defects in the roofing or construction. |
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Insect
pests have been known to infiltrate electrical panels.
The termite
carton nests above can pose serious problems.
Jack
Leonard – New Orleans. |
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| Additionally, while performing
the pest inspection, the thermographer will encounter
the usual building envelope problems such as missing,
poor or no insulation, outside air intrusion, duct
leaks, heat and cold loss and the usual other thermal
imaging discoveries that are ingredients in residential
or commercial thermal inspections. These findings can
be incorporated into a single inspection or can be
separated into a subsequent inspection, thus providing
the thermographer with a second earnings source from
another inspection. |
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| In addition, since the
use of thermal imaging will permit the ability to see
inside wall structures, the use of the imager to locate
appropriate locations for chemical treatments or for
the remediation of a pest problem is an essential tool.
As can be seen in the image at the right, assume that
an infestation has been found in a cathedral ceiling,
the usage of a thermal imager will permit the placing
of the required treatment chemicals in the required
locations. If a section is missed, it may provide harborage
for the insect pest to survive. |
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Additionally, as part of any pest treatment
program, two factors for a successful treatment are necessary.
One, if there was a contributing factor such as moisture
providing conducive conditions, the contributing factor
must be removed. Use of the thermal imager will confirm
that the moisture issue has been resolved. Secondly, once
treatment has been effected, it is customary and of good
practice to confirm the effectiveness of that treatment.
The thermal imager can play a role in that confirmation
process, but again, is but one of the tools to be utilized
in the process.
Verification of Data or Findings
In the inspection process for insect pests, it is important
to understand that the detection process also includes
the verification of the data or the findings. Digital and
IR images need to be captured and recorded. Use of additional
equipment to verify the findings and to ascertain the presence
or not of the suspected insect pest is an absolute must.
The following is a brief list and description of some equipment
that can be used to provide and verify data and results:
Moisture Meters:
Locating the presence of latent moisture is not
enough. A pest thermographer must then confirm the
presence and level of moisture. Usually, a moisture
meter will be employed.
Tramex Moisture Meter |
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Microwave Detection Equipment:
Termatrac® is a hand-held portable detection
device using patented microwave technology. Termatrac® can
detect insects and other pests in unseen areas such
as wall voids, cracks, crevices, air pockets, construction
flaws, beneath floors, and in ceilings, etc. Termatrac® will
detect activity through a variety of materials such
as brick, wood, stucco, concrete block, ceramic tile,
marble, terracotta tile, mica, plastic veneers, vinyl
and many other materials. Termatrac® is non-invasive
and non-destructive, thereby avoiding damage to a
client’s property. |
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Acoustic Emissions Detection
Equipment:
AED 2000L is a portable hand-held instrument that
is the most advanced and sensitive acoustic detection
system for locating termites and hidden insect pest
infestations in wooden structures, trees, plants
and soil. The AED, a product of several years collaboration
with the USDA Agricultural Research Service literally
permits the user to listen to the insect pests eating
their way though wood or even in some cases walking. |
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Structural Test Equipment:
The Resistograph is an instrument that is utilized
to measure the structural integrity of wood structures.
Utilizing a very fine drill, the Resistograph, as
the drill penetrates the wood structure at a predetermined
rate and torque, measures the resistance and changes
in torque to provide a printable data record of the
probing actions. If there is an insect pest gallery
present or if there is wood decay, the Resistograph
will provide the data necessary to make a structural
analysis of the situation. |
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Boroscopes and Video Imaging
Boroscopes:
Boroscopes, both manual and video imaging, can provide
crucial confirmation of the presence of insect pest
infestations. Inserted through a tiny hole, the boroscope
probe can be manipulated to the suspected area of
infestation where visual confirmation can be obtained.
Either video or digital imaging cameras can be utilized
to record the findings. |
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Special Challenges
For the Infrared Pest Thermographer there are special
challenges that need to be met and unusual occurrences
possible within any inspection and some of these items
should be treated as specific subjects to be discussed
at length at another time.
There are however, some special challenges that need to
be mentioned and repeated from above:
