COURSE Termites An Uninvited Guest with Pictures.pptx
TERMITES: AN UNINVITED GUEST
Not all of the termites in a colony have eyes. Subterranean termites live
underground- where there is no light. When they do leave their underground colonies
to forage for food that is located above ground they travel from the ground to the
house in tubes that they construct. There is no light inside these tubes. The termites
exist inside of the wood in the house in tunnels that they have carved out with their
mandibles (their jaws), and there is no light inside these tunnels. The worker spends
its entire life in the dark (if you want to apply a scientific name to "living in the dark" you can call it "cryptobiotic", which
means, literally, hidden living.
So, why have eyes? If you were to go into a cavern far enough so that there was total darkness, and stay in that cavern
for the rest of your life, you would not need eyes either. There must be some light for eyes to be able to function. So, how
do the worker termites make their way around? There are two ways in which termites are able to navigate, and those are
by their sense of touch and their sense of "smell".
First, they feel their way around - with their antennae - in much the same way a blind person might navigate with the use
of a cane. The worker termites are blind. So are the soldier termites who spend most of their time inside of the colony.
The individuals in the termite colony that do have eyes are the "reproductives". They swarm out of the colony at certain
times of the year and they are attracted to light with their compound eyes. They cannot see anything as long as they are
confined to the inside of the colony, but once they emerge into the light they are attracted to the brightest spot available.
That is why when termites swarm from a subfloor in a bedroom they are attracted to the window. It was the source of a
bright light. Termite species that may swarm in the evening, such as Dampwoods or Formosans, may be attracted to the
light on a front porch, causing tremendous anxiety for the homeowner, who may wonder whether they have a problem in
their own structure.
Many times a homeowner will call a termite control company and complain about termite infestations in their window
sills, because they see the termites in the window but in actuality they have swarmed out of the colony somewhere else in
the house and are attracted to that window which is the brightest source of light in that room. The eyes of the termite
reproductive are compound eyes that cannot see objects sharply, like we can, but they can readily detect a difference in
light intensity, such as when a cloud passes overhead and casts a shadow on their exit tube. That shadow may indicate
danger to them, and the colony immediately stops giving off swarmers.
There are some specific structures on the heads of termites that allow you to determine accurately
which kind of termite you are dealing with. These are the "fontanelle" and the "ocelli", which are
simple eyespots that may be located next to the compound eye. These are found as follows:
Dampwood termites - have neither ocelli nor fontanelle
Drywood termites - have ocelli but not a fontanelle
Subterranean termites - have both ocelli and fontanelle
So, what are we talking about here? Well, the fontanelle is simply a little spot located right in the
middle of the top of the head. It oozes out an irritating fluid when the termite is threatened, and thus
is a defensive mechanism. The ocelli are simple eyespots located just to the inside of the compound
eyes, and likely detect some shades of light and dark. Since color and size are not always consistent
characters for identifying the type of termite, it is worthwhile to have other, specific features as well.
A second means of navigation by termites is by their sense of smell, and the use of chemical odors called pheromones.
These chemicals are given off by termites as they forage for food, and are detected by other workers who can follow the
chemical trail, just like a bloodhound following the scent of a human, to the food source and back to their colony. We will
discuss this further in the next section.
The antennae of termites look like marshmallows or beads strung on a wire. If you look at them through a high powered
lens you will see that they are covered with bristles (or hairs). This type of antenna is called "moniliform" antennae, and
means that all of the segments look the same - there is one ("mono") shape and size to each of the segments.
These antennae are very important to the termite, because several senses are located in the antennae. The sense of
touch enables the termite to feel its way around in total darkness, as it "sees" the surfaces and objects it encounters. It
also enables termites to "talk" to each other. When they meet face to face in a dark tunnel they exchange information by
touching their antennae together. Their sense of taste also is located in their antennae, and as they touch something in
their environment they can taste it. Their sense of smell is located in their antennae, and it is here that their Pheromones
become important tools for communication.
After emerging from the colony the male swarmer, for instance, locates the female swarmer by following the scent she
gives off when trying to attract a male. His antennae zig and zag around frantically until he finds her, and once he has
accomplished this task he glues his nose to her and follows her everywhere, until she at last finds a location suitable for
her to establish a new colony. So, if you snipped the antennae off of a subterranean termite worker it would not be able to
see, talk, taste, or smell. If you snipped the antennae off of a male subterranean termite swarmer he would not be able to
carry on his courtship ritual. Everywhere one of the tiny little hairs on the antenna attaches to the cuticle (that outer shell
of an arthropod) it does so at a tiny opening to the body. At this opening are sensitive nerve cells, which detect the tastes
and odors so important to the termite.
We, as pest control professionals, learn as much as we can about the anatomy and biology of the pests we deal with, and
this is one area that sets us apart from the untrained members of the public, and is the reason we have the advantage in
our ability to control those pests. We learn to recognize that the termite has moniliform antennae, while ants have
"geniculate" (elbowed) antennae, with a 90-degree bend at their middle. This feature easily separates the two kinds of
insects for our identification purpose. Since both ant and termite swarmers will shed their wings following swarming, and
since the small, black subterranean termite reproductives may be confused with some of the small black ants, knowing of
specific differences is vital for proper control.
The mouthparts of a termite perform several important functions. The first one we think of is chewing down our house.
There have been many studies about how much wood a termite can "eat" in a day, and it really isn't very much per
termite, but remember that termites never sleep. If a termite has the assignment of enlarging a chamber in the wood or
extending a tunnel, the work will be done on a 24-hours-per-day basis. And, when you think of the fact that a percentage
of the 500,000 termites in the colony have that assignment, added together it can amount to quite a bit of damage in a
short period of time.
But termites, strangely, cannot digest the wood they "eat" (like we would digest a hamburger). The main ingredient of
wood is cellulose, and termites, like many animals, cannot digest this tough material. To accomplish this feat they have in
their gut a population of one-celled animals called protozoa, that secrete enzymes that break cellulose down into starch,
and then other enzymes that break the starch down into sugars, and that is what the termite can digest by itself - SUGAR.
They absorb the sugar through the wall of their intestinal tract and use it for their energy. Without this population of
protozoa in their gut the termites would soon starve to death.
The term for a relationship between two different organisms is "Symbiosis", and there are several kinds of symbiosis. One
is called "Parasitism", where one side benefits at the expense of the other - mosquitoes would be a good example of
parasitic symbiosis. Another is called "Mutualism", whereby both sides benefit, and this applies to the termites and their
protozoans. Actually, symbiotic protozoa have been found in some other kinds of insects as well, such as some species of
cockroaches, so it apparently works pretty well.
When the "baby" termite (first instar nymph) hatches from its egg its intestines are sterile - it is not born with a population
of protozoa in its gut. It soon acquires its own population, or inoculants, of protozoa, however, by licking the bubble of
liquid that oozes out the rear end of the termites that have been in the colony for awhile, a method of feeding called
"proctodeal feeding". Protozoans are present in this liquid, and the tiny nymphs now have the means for digesting their
Our knowledge of this process is an important factor in the control of Drywood Termites. One of the primary controls we
have for these termites is fumigation. Fumigation is not particularly efficient at killing the eggs of the termites, but offers
some excellent benefits otherwise and is highly effective at killing all the workers and other members of the colony. If all
the workers are killed, the newly emerging nymphs will have no way to acquire their first dose of the protozoans, and they
die quickly as well.
Another function of the mouthparts of a termite is the "grooming" of other termites in the colony. They lick each other's
bodies clean of dirt and mold, and in the process exchange bodily secretions. Thus, if a termite has walked through a
pesticide dust and has some on its body, it will be imbibed by other termites in the grooming process, and of course will
kill those other termites in due time. One account of termite grooming that I read offered the gruesome tale of just how far
this can go. The researcher observed a termite worker grooming another worker and saw what appeared to be overly
aggressive grooming. The termite doing the grooming actually nicked through the cuticle of his companion, apparently
found the taste to his liking, and proceeded to consume the entire termite.
As technologies improve along with our increased knowledge of the termite biology and the functioning of their colony life,
we again take advantage of the termite habits themselves, in our control programs. In the process of grooming the
workers remove bits of fungi from each other, fungi which might otherwise cause illness and death in the termite. A fairly
new termite chemical is on the market, called Premise, which alters this grooming habit. The workers that have been
exposed to Premise no longer groom each other, and Nature's own control measures take place, with many of the
termites dying from natural diseases.
Another form of feeding provided to 1st instar nymphs is called "stomodeal feeding", and refers to workers regurgitating
some of their pre-digested food for the benefit - and enjoyment - of the new nymphs. The contents of the alimentary canal
of one termite are deposited into the mouth of another hungry termite, and it also is referred to as trophallaxis. In the
process sugars are passed along through the colony as well as any pesticide that happens to be in the food.
Another function of the mouthparts of the termite worker is to lick off the outside of eggs that the Queen termite has
produced, and to stack them in the cell that has been prepared for them. The workers transport the eggs just like a mother
cat transports her kittens - by picking them up in their mouth and placing them where they belong. Remember that a
termite colony in the ground is liable to be a very damp place, very conducive to the growth of molds and fungi. It is the
job of the termite worker to keep the eggs in a healthy, semi-dry state.
Another function of the mouthparts of a subterranean termite worker is the construction of the tubes or tunnels that allow
the worker termites to travel from the colony in the ground, up over a concrete foundation, and into the wooden structure
of the house without ever emerging from the darkness of the tunnel. These "tubes" are made of soil and liquid excrement.
The process is much like we would use in building a brick chimney. A mouthful of sol is placed down and a drop of liquid
from the rear end of a termite is placed on top of it (just like a bricklayer would place mortar). Then, another mouthful of
soil is placed on top of the drop of liquid. This liquid is much like a fast drying model airplane glue, only without the side
effects, and acts to stick the soil particles together. The process is repeated again and again, and behold, a tube is
formed. Termites work together to get this task done, and it is amazing how substantial a tube can be built in a very short
The mouthparts of a soldier termite are modified to form a scissors-like instrument protruding from the front part of the
head, and designed to cut off the legs or antennae of an attacker or, in the case of an ant, to cut it in two. These
mouthparts are so specialized for the defense of the colony that a soldier termite cannot even use its mouthparts to feed
itself. It has to be fed by workers in the colony through trophallaxis (which we already have defined.) Some species of
termites have workers with, instead of jaws, a hollow tube. Rather than grappling with an intruder these nasutitermes
termite soldiers are primarily tropical, but two species may occur in the southwest United States. They have large, bloated
heads with a tubular mouth, and when threatened they spray out a sticky material that entangles their enemy, with the
potential of shooting up to 1 inch possible.
The Thorax, Wings and Legs
So much for the functions of the various parts of the head of the termite. Now, let's move on to the thorax, which is located
just behind the head. This is where most of the muscles are stored that enable an insect to run or fly. Thus, it is the place
where the legs and wings of an insect are attached.
In classifying insects into their respective ORDERS, wing structure often is used. Those of you who do crossword puzzles
will run across a clue that says "wing" or "wing-like structure". The puzzle is looking for the Latin word for wing, which is
"ALA" in the singular, or "ALAE" in the plural. Alar would mean wing-like, and the winged reproductive caste of termites
are often referred to as the "Alates". However, the ORDERS of insects use the Greek word for wing, which is "ptera". So,
when you read the name of the order to which a particular insect belongs you will see "ptera" in that name. Ptera is
combined with other letters that describe the wing of that insect.
Flies belong to the Order Diptera. "Di" means two, so all members of the Order Diptera have two wings.
Bees and wasps belong to the Order Hymenoptera. "Hymen" means clear membrane, so all members of the
Order Hymenoptera have clear, membranous wings.
Beetles belong to the Order Coleoptera. "Coleo" means sheath, so all members of the Order Coleoptera have
hard, sheath-like forewings.
Butterflies and moths belong to the Order Lepidoptera. "Lepid" means scale, so all members of the Order
Lepidoptera have tiny scales on their wings, which form color patterns distinctive to each kind.
Termites belong to the Order Isoptera. "Iso" means equal, so all members of the Order Isoptera have four wings
of equal length. (This will differentiate them from bees, wasps, and ants, which have 4 wings, but the front pair of
wings is longer than the hind wings.
It is only the adult male and female termites (the swarmers) that possess wings. Termites are not strong fliers, and when
they land after a short flight they use their mouthparts and front legs to tear their wings off at a pre-stressed line at the
base, leaving only the short stubs attached to the body. They no longer need their wings, and the wings would just get in
the way during courtship, new colony establishment, and future movement within their enclosed galleries. It is the
presence of these short wing stubs that helps us identify the bug we are dealing with as a termite, and separates it from
some similar looking beetles, called Rove Beetles, that also have very short wings.
Termites, being insects, have three pairs of legs - that is, 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.
The third major section of an insect, the abdomen, is located directly behind the thorax. In the case of a bee, wasp, or ant
the abdomen is joined to the thorax by a thin "thread-like" structure called the "pedicel", or commonly referred to as their
waist. In the case of a termite the abdomen is broadly joined to the thorax, without the thin waist, and this provides
another easy way to differentiate an ant from a termite.
The abdomen of a termite has several important functions. The obvious one, of course, is its involvement in sexual
intercourse, which guarantees the continuance of the species. A less obvious function is the part the abdomen plays in
the building of the mud tubes that extend over the foundation walls of infested homes. In the case of Drywood Termites
the contents of the large intestine are squeezed dry, and the liquid reabsorbed through the intestine wall. The Drywood
Termites live in wood with very little moisture content, and they need to conserve every bit of moisture they possibly can in
order to survive. Thus, the Drywood Termite squeezes out a hard, dry pellet.
In the case of the subterranean termites water is added to the contents of the large intestine, and the termite squeezes
out a slurry which is fairly fast drying, and is used to cement together the particles of dirt that are used in construction of
their tubes (tunnels). Subterranean termite workers, who are working above ground in a structure, return regularly to their
below-ground colony, not only to return food material to the colony, but also to replenish their moisture supply and to
In the insect world we learn to "never say never", and odd-ball things show up at times that seem completely out of
character. I once had a termite operator show me some "tubing" that he had found in a wooden crate in his mother's
backyard. Termites were moving through this tubing, but the tubing was composed of Drywood Termite fecal pellets all
stuck together, and the termites that were using this convenient pathway were distinctly DRYWOOD termites. Now, these
termites are not supposed to make tubes, but in consulting with one industry expert on it his reply was "Sure, why not? If a
termite needs to get from Point A to Point B, and stay hidden in the process, they will do
whatever is necessary to get there."
Formosan Termites carry this to an extreme, using their body liquids mixed with chewed up
wood to create "carton", an extremely hard matrix that may fill entire wall voids, and which is
used for their living quarters.
Now, let's take a look at the different types of individuals, or "castes", found in a subterranean termite colony. They
fall into three categories. By far the most numerous are the "WORKERS" of the colony. As the name suggests, they do all
the grunt work of the colony. They take care of the eggs that the queen produces, keeping them clean and dry and
healthy. They feed the little baby termites that hatch out of the eggs with material that they regurgitate into their mouths.
These "baby" termites that have just emerged from the eggs are in what is called the "first instar" stage. They are
unable to feed themselves and have jaws too weak to chew off wood. After a short while their "exoskeleton" starts to
harden like a suit of armor.
Human beings have what is called an "endoskeleton", or in other words a skeleton on the inside of us. We have head
bones, arm bones, leg bones, and most of us have backbones. These bones are covered with a layer of muscle that is
covered by a layer of fat (some of us are blessed with more of this layer than others are), all of which is covered with a
layer of skin so that, when you look at each other, you do not see our skeleton at all.
Insects, on the other hand, have a skeleton on the outside of their body, made up of a material called "chitin". This
skeleton is a protective covering, much like a suit of armor, that is relatively impervious to intrusion by things from the
outside. When an insect wants to grow bigger it has to lose that suit of armor somehow, being softer and pliable for a
day or two, expanding, and then forming the new exoskeleton. The termite nymph has the ability to split the suit of
armor right down the middle of its back, and then it steps out and leaves the old skeleton behind. It now has a new
skeleton one size larger! The process of getting out of its old skeleton is called molting, or "ecdysis". The stages
between molts are called "instars". A termite molts six times, so that it has seven instar stages, the seventh one being
the fully developed adult, possibly a worker, a soldier, or a reproductive.
In subterranean termites there is an adult stage called the "Worker", while in Drywood and Dampwood Termites all of
the nymphs ultimately become either Alates or Soldiers. There is no adult worker caste in these groups, and all of the
workers are simply immature nymphs.
When the immature termites reach the third instar stage they are able to survive on their own, and are therefore put to
work. Some of them serve to attend the Queen, some of them nurse the young termites, some of them feed the soldier
termites. Some of them chew through the wood, extending the excavations and thus eating away at the wooden
structure of the house. Some of them work to build the tubes that extend up over the foundation walls. All of them have
a job to do. When they reach the fifth instar stage some of them begin to be modified into soldiers or reproductives,
while the rest of them stop development and remain as workers for the rest of their lives. The average lifespan of a
worker termite is two years. Since the Queen continues to lay eggs all day and night for fifteen years or longer, the
workers that die are replaced quickly, and the colony grows in number.
The second member of the caste is soldier termites. They have no other function than the protection of the colony.
When the swarmers are about to fly out of the colony, or if a breach in the colony occurs, a hole being produced in the
tubing that would allow enemies in, you can observe the soldiers with their large mandibles quickly ringing the exit or
opening. They stand there in a highly protective stance, and if an ant were to intrude at that point it would merely be cut
in two by the large, scissors-like jaws of the soldier.
Now, of course, there are drawbacks to any lifestyle, and there is one job hazard that the termite soldier must contend
with. I watched an excellent nature program one time, on the life of termites, where a hole was created in a termite
colony's mud tubing, ants threatened to enter, and termite soldiers immediately rushed to defend. As they stood outside
the hole, gallantly waving their massive jaws and daring any ants to approach, the workers sealed up the hole behind
them, leaving 4 or 5 workers stuck outside, their predicament beginning to dawn on them.
The third type of individual found in the colony is the reproductive, or "swarmer", sometimes called the "alate"
(borrowing from the Latin word for wing - ALA). These individuals have gone through six molts of their exoskeleton and
are now full-grown adults capable of sexual reproduction. Their function is to exit from the colony, mate, and establish a
new colony separate and independent of the one that they just left. And, herein lies an interesting story.
These fully grown, sexually mature adult termites are produced in the colony year round. They are a result of the sixth
instar termites molting for the last time. They accumulate in the colony and are fed by the worker termites. As the time
draws near for them to exit the colony en masse they crowd around the exit tubes built by the worker termites.
What causes them finally to exit from the colony? There are three major stimuli that cause the subterranean termites to
A sudden increase in the humidity inside of the exit tubes
The proper temperature outside of the exit tubes
The proper light intensity outside of the exit tubes
When you consider that the major swarming in the springtime is on a nice sunny morning just after a rain, you can see
that such an environment fulfills the three conditions listed above. First of all, it has just rained. This may have been a
heavy rain that has lasted several days or it may have been a light shower. At any rate, the rain has increased the
humidity inside of the exit tubes. This sends a message to the swarmers that the ground outside probably is soft and
easier to dig into than if it were dry and hard. The soft dirt increases the chances for success in excavating a pocket in
the soil, and thus increases the chances for survival of the species. Somehow, the termite swarmers know that.
Second, the proper temperature - around 70 degrees F, plus or minus a few degrees - must be present. An increase in
humidity in the exit tubes could exist because of a snow storm or because of a rainstorm followed by a severe cold
snap. Termite swarmers will die off from the heat on a hot, dry day before they can find their way back down into the
ground, or they may freeze to death rather quickly if the temperature is too low. In these cases, swarming will not occur.
A nice, gentle temperature just after a rain is most suitable to the swarming process.
Third, the proper light intensity must be present outside of the swarming tubes. This light intensity occurs on a warm
spring morning, just after a rain when the clouds clear away and the sunshine comes beaming through. When these
three conditions mesh it appears to the termite swarmers inside of the tube that the time is right for an exit from their old
colony. Remember, that it is only a small percentage of the termites in the colony that swarm at any one time. The
colony continues to live on, the workers continue to do their assigned tasks, and more swarmers mature for the
following swarming season. It is well to remember that a colony does not give off swarmers until the colony is at least
three years old. By that time there are enough termites in the colony that it can afford to lose large numbers to the
So, out they come, flying toward the brightest light, which usually is the sun. If the colony was well-established there will
be hundreds of swarmers emerging. Half of these are males and half of them are females. Termites are not strong
fliers, and if they were to fly a hundred yards it would be considered a strong flight. Sometimes a prevailing wind will
blow them a little farther, and usually in the direction of the wind. When they finally land on the ground their first action
is to break off their wings. The wings are no longer needed, and might get in the way in courtship or colony
development. You might read in literature that the wings are shed as soon as the termites find a suitable place for a
new colony, but I have found termite wings on the window ledge of my car, and I certainly hope they did not set up shop
near that location.
The wings have a suture near the base of the wing, much like the pre-stressed line on the statement from your
department store. You tear off the top of the statement along this line, and return it with your check. The termite tears
off its wings along this pre-stressed line too, using its mouthparts and its front legs. The wings are easily discarded, and
now the male is ready to find a female termite. The female is ready too. She lifts the end of her abdomen up high and
emits a perfume (a sex pheromone) from the tip of it to attract the male. As you recall, the male uses his antennae to
smell with, and when the male smells this delicious perfume his antennae zig-zag furiously, and he starts running in
circles, each circle getting smaller until he finally finds the source of the smell - the female termite.
At that point in time the female lowers her abdomen and the male places an antenna on each side of the female's
abdomen, and they walk off together, the male following the female who is looking for a suitable place to excavate their
nuptial chamber. This may be under an old board on the ground, alongside an old tree stump, alongside a foundation
wall, or a hundred other places where the ground is soft and the digging is easy. They then work together to excavate a
hole in the ground, by using their mandibles (jaws) to move a tiny piece of dirt at a time, until they have created a cavity
large enough for them both to fit in and to move around. Then they close the door to this chamber in the same way that
the worker termites build tubes - they stick bits of dirt together with anal secretions until they have formed a nice, snug
little nest once again, hidden away from the rest of the world and secure from their enemies.
It is at this time that the male and female termites mate. This pair lives together in the colony for years, with the male
inseminating the female at intervals. Over time the original Queen develops an extraordinarily expanded abdomen, as
her ovaries expand tremendously to support the huge volume of eggs she lays daily. Other queens, called "secondary"
queens, also develop, and produce small amounts of eggs themselves, but the primary queen does the bulk of it.
This entire process of swarming, pairing off, and digging their way back into the earth may take a few minutes or a
couple of hours at the most. It is during this swarming process that the termites are exposed to their enemies. Birds and
lizards pick them off, dragonflies and robber flies dine on them, and ants have a field day with them. It is also the only
time that humans usually see termites. The rest of their lives are spent in a cryptobiotic existence - hidden away in the
ground or in tunnels in the wooden structure of your house.
Photos courtesy of photographers published on Bugwood.org ITP Node
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