TERMITE I.D. Subterranean; Drywood & Dampwood
The ability to properly identify the key physical characteristics of various species of termites can mean the difference
between a job well done and a costly lawsuit. Termites, being insects, have three pairs of legs, three legs
attached to one side of the thorax and three legs attached to the other side. The termite's wings are attached to the
upper side of the thorax, whereas the legs are attached to the lower side of the thorax. The muscles that cause the
wings and legs to function are located within the thorax.
TERMITE ANATOMY. Correct identification of the four types of structure-infesting termites is not difficult. This article
will discuss the identifying characters of these termites in easily understood terms.
In order to identify termites, you must be familiar with the various body parts used in identifying these insects. Termite
colonies are characterized by several different castes or forms of individuals. The alates (swarmers) and the soldiers
are the individuals in the colony which can be used for identification purposes. A technician, therefore, must have
either a soldier or an alate if he wishes to identify the termite involved.
Alates. Termite alates closely resemble the winged reproductives produced by ant colonies. All four wings of termite
alate are the same size. The hind wings of an ant swarmer are much smaller than its front wings. The termite alate's
waist is broad in shape while the ant swarmer's waist is pinched or narrow. The antennae of the termite alate are
straight. An ant swarmer's antennae are elbowed.
The primary difference between the various species of termites is seen in the wings. A hand lens is needed to see the
Identifying characters of the termite's wings. When a termite alate specimen is found, the wings should be removed and
placed on a piece of white paper. A pin or needle may be needed to hold the wing flat on the paper so the veins in the
wing can be examined fully.
Many times, only wings are found in window sills. Even if only wings are found, identification of the type of termite
involved can still be determined. What follows is a discussion of the identifying characters of the various types of termite
1. Subterranean termites: There are four types of tubes:
working tubes are constructed from the nest in the soil to wooden structures and they may
travel up concrete or stone foundations;
exploratory and migratory tubes arise from the soil but do not connect to wood structures
drop tubes extend from wooden structures back to the soil; and
swarm tubes (migratory) for new and swarming reproductive kings and queens to emerge from
and fly away during swarm season.
If you break termite tubes open, you may see live workers and soldiers running through the tubes.
The darkening or blistering of structural wood members is another possible indication of an infesta-
tion; wood in damaged areas is typically thin at the surface and easily punctured with a knife or
screwdriver. Finding live termites foraging within wood is a sure sign of an active infestation.
The excavations that termites make in wood are hollow, completely enclosed, more or less longitu-
dinal cavities. Some species deposit light-brown excrement within cavities. Feeding in wood by sub-
terranean termites generally follows the grain of wood; these species attack the softer springwood
and leave the harder, less digestible summerwood. Many times this distinctive pattern of wood dam-
age alone can be used to positively distinguish subterranean termite activity from that of other spe-
Subterranean termites: require moist environments. To satisfy this need, they usually nest in or
near the soil and maintain some connection with the soil through tunnels in wood or through shelter
tubes. There are instances where slow leaks inside wall cavities will allow termites to form a satellite
or sub colony above ground and eliminate the necessity for returning to the soil. Because of the
moisture requirements of subterranean termites, they are often found in wood that has been slightly
decayed. Soil serves as a source of moisture that protects termites from desiccation, shields them from predators, and
can be used as a building material for shelter tubes. Termites can also excavate passageways through the soil to reach
additional food sources. If a new food supply is found, then more individuals are recruited to the site. After a while, a sub
colony is established with a continuous exchange of foragers between this group and the main portion of the colony. Then
for any number of reasons, the sub colony may be cut off from the mother colony; and the exchange of individuals termi-
nated. This sub colony has the capacity of producing its own reproductives and developing rapidly as an independent co-
lony. Because subterranean termites usually do not build their nests in wood, they must forage for food away from the
nest. In most parts of the country, foraging is essentially curtailed by winter or extremely dry periods. The amount of wood
consumed generally increases with increasing temperature. The optimal conditions for foraging, warm temperatures and
high soil moisture, are usually present under and around buildings. A consistent moisture source inside a building along
with temperatures that remain more constant allows subterranean termites to flourish year around.
One of the chief means of shared feeding is called trophallaxis or the mutual exchange of gut contents between colony
members. Trophallaxis also permits the efficient use of nutrients, recognition of colony members, distribution of chemicals
involved in caste regulation, and the transfer of cellulose-digesting protozoans. Many members of a termite colony cannot
feed themselves, so they rely on other colony members to feed them. This behavior also facilitates the transfer of tox-
icants used in baits and other insecticides.
Subterranean termites live and invade from underground, and a single colony can spread out over an acre underneath a
home. A home with a footprint of 2400 square feet could have several termite colonies with hundreds of thousands of fo-
ragers seeking food and shelter.
2. Drywood termites: Drywood termites are cryptic insects that are difficult to detect. They live deep inside wood; and
except during periods when they swarm or when repair work is being done on infested homes, they are seldom seen. Co-
lonies are small (usually fewer than 1,000 individuals), can be widely dispersed, and take years to mature. The most
common sighting of drywood termites is flying adults (called swarmers) that occur during early evening hours during late
spring and summer months. The wings of drywood termite alates differ from those of subterranean termites by having
three or more dark veins at the upper margin of the wings instead of only two veins. The body color varies among the
different species of drywood termites. Do not attempt to use color to distinguish between the various types of termite
alates. Galleries or tunnels in the wood made by drywood termites cut across the grain of the wood and destroy both soft
spring wood and the harder summer growth. From this infested wood, winged reproductives
periodically swarm to infest additional nearby wood. Nests of most species remain entirely
above ground and do not connect to the soil. Feeding by dry wood termites can cut across
the grain of wood leaving a characteristic pattern of chambers and tunnels, some of which are
filled with fecal pellets. Drywood termites often expel their fecal
pellets through surface openings and they can accumulate on ho-
rizontal surfaces below the openings. These fecal pellets, which
are distinctive in appearance with six longitudinal flattened sides,
may be the first clue to their presence.
Dampwood termites: The alates of dampwood termites are
quite large, up to 1 inch long or more including the wings.
There is no worker caste in dampwood termites and the nymphs perform all the tasks
typically done by workers. Like the drywood termite alate, the dampwood alates wings
have four dark veins at the upper margin of the wings. Fecal pellets are about 1/32"
long and colored according to the wood being eaten. The pellets are usually very simi-
lar in shape (elongate oval) to those of drywood termites but with the six sides flattened
instead of being concave. If the wood is very damp, the pellets may be spherical or
round. The dampwood swarmer can be distinguished by its large size and the fact its
antennae will have more than 23 segments. The nymph dampwood termites take care
of the kings and queens of the colony and feed the soldier caste. These termites create
a series of chambers in wood, which are connected by tunnels with smooth walls, as if sandpapered. Dampwood termites
are usually found in logs, stumps, dead trees, fence posts, utility pole and decks with contact to the ground. Dampwood
termites as the name suggests must have damp wood to survive. Dampwood termites require wood with a high moisture
content. Wood in contact with the ground or with a constant moisture source is most prone to attack. Dampwood termites
attack the wood directly from the soil and usually do not burrow into the soil.
Dampwood termites do not create shelter tubes as with subterranean termites. The appearance of timber damaged by
dampwood termites can be varied but they always eat across the grain, consuming both spring and summerwood. While
doing this, they make a series of chambers or galleries connected by tunnels whose walls are smooth as though they are
finely 'sandpapered'. There is no soil in the galleries, but if conditions are extremely damp, the fecal pellets will stick to the
gallery walls and appear as soil. If conditions are dry, the fecal pellets accumulate at the bottom of the galleries or are ex-
pelled from the galleries in the same way as drywood termites do. Dampwood termites often use their fecal pellets to seal
off their galleries in order to maintain a high level of humidity in the gallery system.
Soldiers. Soldier termites are identified by examining the shape of the head and the mandibles. A soldier termite's
head is enlarged and hardened, giving it a dark appearance. The color can vary from light brown to black depending
on the species involved. Except during the swarming season, a soldier termite must be found in order to identify the
species involved. In some cases, this will involve breaking wood apart to locate a soldier.
What follows is discussion of the differences between the various types of termite soldiers.
1.Subterranean termites: Subterranean termite soldiers have a rectangular shaped head
which is tan in color. The mandibles do not have any teeth along their inner margins. A
few species may have only a single tooth on one mandible.
2. Drywood termites: The head of the drywood termite soldier is rectangular in shape like
the native subterranean termites. The mandibles of the drywood soldier, however, have
teeth present along the inner margins of both mandibles.
3. Dampwood termites: The soldiers of dampwood termites are quite large except in newly
formed colonies where the soldiers may be much smaller. Like the drywood termite
soldier, the dampwood soldier has a rectangular shaped head and teeth present along
the inner margins of both mandibles. The antenna of the dampwood termite soldier, how
ever, usually has more than 32 segments.
Identification by fecal pellets (frass)
Photos courtesy of photographers published on Bugwood.org ITP Node
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Dampwood termites Subterranean termites
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