Introduction to Termites
Subterranean
termites are the single greatest economic pest in the United States. They
cause billions of dollars in damage each year to homes, historical structures,
and commercial buildings. In addition to buildings, termites also consume
valuable books, documents and photographs.
Subterranean termites have existed for over 55 million years and are extremely good at what they do. A great deal of their success can be attributed to their cooperative behavior.
Subterranean termites are social insects. This means that they live in family groups called colonies. Social insects are different from other insects (grasshoppers, cockroaches, or beetles) because each termite in the colony performs a specific job that benefits the colony as a whole. Most other insects work only for themselves. For example, each individual grasshopper will feed and reproduce itself independently of its siblings. In the termite colony an entire group or caste of termites is responsible for feeding their parents and siblings, while another caste is responsible for reproduction. Because of this division of labor, the colony of individuals functions as a single animal.
Colony Establishment & Swarming Behavior
Swarming is the termite method of dispersal and new colony establishment.
The swarmers are new termite kings and queens that must leave their parent
colony in order to mate and establish new colonies of their own. The eastern
subterranean termite, R. flavipes (New England’s only species), usually
swarms in the spring (March-May) during the daylight hours on warm days
following a rain. 
Subterranean termite swarmers are attracted to light. If they emerge
indoors they will be seen flying to windowsills and open doors. Usually,
termite swarming either indoors or outside is the first indication to homeowners
that they have a subterranean termite infestation.
The
termite swarmers pair up during their flight then land and search for
a place to begin a family. Their wings break off shortly after landing
and the new king and queen start their colony by excavating a small chamber
in a crevice or plot of soft soil. From this point on, they will spend
the rest of their lives underground. As the new queen begins to produce
eggs her abdomen grows larger with the development of her ovaries. As
she stretches, the segments of her body pull farther apart showing the
white membranes between the segments of her abdomen. This gives the queen
a striped appearance. At this point she is an egg laying machine. The
colony will continue to grow with increasing numbers of termites being
produced each year. The parental king and queen often survive for a decade
or longer and can produce huge colonies.
Mature colonies (4-6 years old) of R. flavipes have been estimated
to contain more than 60,000 workers on average. Mega colonies have been
recorded with populations estimated over a million. These large subterranean
termite colonies often become decentralized over time and occupy multiple
nesting sites interconnected by a network of underground tunnels.
Subterranean Termite Castes
Queen & Secondary Reproductives
The termite colony originates from a single pair of reproductive
swarmer termites, the king and queen. However, if the king or queen should
die, other individuals within the colony will start to develop functional
reproductive organs to take their place. These individuals are called
secondary reproductives. Secondary reproductives may also develop in
satellite nests where a group of workers have become separated from the
parent colony. This splitting or budding of the nest expands the original
colony's foraging territory. 
Worker Caste
Subterranean termite workers are the caste found feeding on
wood. The workers are responsible for all of the labor in the colony.
They care for the young, repair the nest, build foraging tunnels, locate
food, feed and groom the other castes and each other. The youngest termite
workers perform the tasks inside the colony like feeding, grooming and
caring for the young, while the older more expendable workers take on
the hazardous jobs of foraging and nest building. The termite workers
are both male and female but they are functionally sterile. They are
milky white in color and have no wings or eyes. The body of the termite
worker is soft, but its mouthparts are very hard and adapted for chewing
wood.
Soldier
Caste Subterranean termite soldiers are the defenders of the
colony. They protect the colony against marauding ants and foreign termites.
When foraging tubes or galleries are broken into, the soldiers congregate
around the break to stand guard against invaders. Soldiers are similar
to the termite workers in that they are blind, soft-bodied and wingless.
However, the soldiers have an enlarged, hard, yellowish-brown head which
has been modified for defense. The head has a pair of very large mandibles
or jaws that are made to puncture, slice and kill enemies (primarily
ants). However, the large mandibles prevent the soldiers from feeding
themselves so they must rely on the workers for food.
Subterranean
Termite Behavior
It is not known exactly how subterranean termites locate sources of food but they are very good at it. They are known to find wood that is left lying on the ground in a matter of days. It is thought that the termites forage randomly and continuously by digging a network of tunnels and come in contact with food sources in the process.
The foraging range of a single termite colony is difficult to predict. Some larger colonies may forage over areas the size of a football field.
Swarm Tubes
Foraging termites produce a variety of chemicals called pheromones
that influence their behavior. These pheromones are basically odors
that send messages to other termites in the colony. While tunneling
underground, the foraging termites lay down a trail of pheromone which
they secrete from glands on their abdomen. When a food source is located,
the odor trail is intensified to recruit other termites to the feeding
site.
Utility Tubes
Subterranean
termites frequently forage above ground for sources of cellulosic food
like wood in homes and other structures. In order to protect themselves
from predation by ants and maintain their connection to the soil while
searching for food above ground, termites build long tubes out of mud and
fecal material. Termite mud tubes are sometimes very easy to see and are
one of the best ways to identify a potential termite infestation. Mud
tubes become highways running from the underground termite galleries directly
to the food source. They can cover long distances over the foundation
of a building or along exterior walls to reach the wood inside.
Moisture Needs
Subterranean termites are constantly at risk of drying out; this is why they must live in the soil. Soil has the capacity to hold water for a long period of time and keep the colony moist. When termites forage above ground, they must maintain their connection to the soil so that the workers and soldiers can return periodically to replenish their body moisture. The mud tubes provide the termites with this soil connection.
Nutrition and Feeding
Although subterranean termites can chew through and damage many materials, they can only obtain nutrition from cellulose. However, subterranean termites cannot digest cellulose on their own. In order to digest wood, subterranean termites have large numbers of microorganisms in their gut that convert the wood fiber into usable nutrients. If there were no microorganisms in the gut, the termite could eat constantly but still die of starvation. In the colony most food is shared mouth to mouth (a process called trophallaxis). Foraging worker termites feed directly on wood or other cellulose material then store the food in their gut. They then return to the nest and feed the immature termites, soldiers, and reproductives which cannot feed themselves.