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Termites living in nature convert dead wood and other organic materials containing cellulose to humus.  One-celled organisms in their digestive tracts permit them to digest this organic material.  In nature these animals are very beneficial; however, when homes are built in their natural areas termites are capable of considerable damage. 

Subterranean Termite Wood Damage

What Pest Control Professionals know about these pests helps them to design effective pest control treatments for eliminating subterranean termites

What Is a Termite?

Termites are social insects that ingest wood and other organic materials.  Living in colonies with a caste structure or order, they make their nest in moist soil or other moist environments.

The size of the colony depends on the type of subterranean termite. For example, one type may have 60,000 to 1 million workers while another type may have 350,000 to 2 million.  Environmental conditions such as warmth and moisture are critical for their survival.  

Termite nests may be located at or near ground level or several feet deep. Termites are attracted to moist or decaying wood but will build a nest in solid wood also.  Siding or basements with moisture or water damage are good places to check for Termites. The rate at which they can consume an entire board depends on the kind of subterranean termite, the size of the nest, and the type of wood they are feeding on. 

Termites do prefer the soft wood and will leave the harder wood for the walls of their nest. It is possible for a board to look whole on the outside and the inside to be riddled with the galleries they create for their nest.

The Social Structure of a Termite Colony

Generally, termite colony members include a queen, nymphs or workers, soldiers, supplementary reproductives and primary reproductives (swarmer’s) with each having its own distinctive appearance and roll.


Subterranean Termite WorkersIn most of the more primitive species nymphs typically work on nest building, food gathering and feeding of the reproductives and soldiers.  In species with workers, the older nymphs usually do much of the work. Workers and nymphs of subterranean termites perform all of the work in the colony and are the forms that do damage to structures.


The soldier’s only job is to defend the colony against enemies.  They cannot eat wood and along with the reproductives are fed by the workers.  Both the workers and soldiers are blind.


Subterranean Termite Winged AdultWinged adults are the primary reproductives (often called swarmer’s) and emerge for colonizing flights during certain seasons of the year.  During this time the male (king) and female (queen) will pair up, shed their wings, and construct a small cell in the soil.

They will then mate, lay eggs, and rear the first group of workers. In colonies where primary forms are no longer present supplemental (or secondary) reproductives will occur.  Each termite colony is self-supporting and independent of other colonies.

The Termite Life Cycle

Subterranean Termite Life CycleTermites develop through a gradual metamorphosis from eggs to nymphs. The nymphs will go through several molts and develop into the different members or casts of the colony such as workers, soldiers, winged (primary) reproductives and supplementary reproductives.  In new colonies, nymphs from the first small batch of eggs usually all become workers and other forms are not normally produced until later egg laying.


In termite species that include a distinct worker caste, workers are the most numerous and perform the work of the colony such as grooming the queen, excavating the nest, and making tunnels.  To form the nest, they chew and ingest the wood, weakening the structural integrity of the wood and causing costly damage to the structure.

Soldier Termites

Soldier termites function specifically to protect the colony.  Their heads are large and hard, and their jaws are larger than in other forms.  Intrusions made into termite nests or tubes gathers the soldiers together with their mandibles facing outward to protect the colony from invaders.  Lining up as if at war.

Supplementary Reproductives

Unlike primary reproductive supplementary reproductives are wingless or have only very short nonfunctional wings.  They develop as needed and quickly replace a primary queen who is injured or dies.  Supplementary reproductives may also develop in addition to the queen and become the most important source of eggs for the colony.  When isolated from the main colony supplementary reproductives with a group of males and workers may establish a new colony without being visible above ground at any time.

Primary Reproductives (Swarmer Termites)

The Termites that are most often seen by homeowners, and usually much darker than the other colony members, are the Primary reproductives.  Also called Swarmer Termites they have four wings the same length that extend more than the length of the body beyond the tip of the abdomen.  They usually require about 12 months of progressive growth to develop.

The males and females leave the colony in great numbers called swarms, usually in the spring or fall.  Often these swarms are the first visible indication that termites are present. Environmental conditions such as temperature and moisture (both within and outside the colony) must be just right before a swarm.  Generally, a swarm emerges on a warm, sunny day when the humidity is high.  After a brief flight, they shed their wings, males and females pair up and attempt to establish a new colony.

Distinguishing between Subterranean Termite Swarmers and Carpenter Ant Swarmers

Swarmer termites can be confused with flying or swarmer ants.  Three ways to determine if it is a termite are:

  1. Ants have a very thin waist between the thorax and the abdomen, while termites have a broad waist.
  2. Termite wings are all the same size and shape, and the forewings of the ant are larger, longer and of a different shape than the hind wings.
  3. Termite antennae are straight; ant antennae are elbowed.

The Termite and its Environment

Termites require moist soil and a source of moisture to survive. This is critical to termites because all castes except the primary reproductives(swarmers) are soft-bodied insects that lose water rapidly upon exposure to dry air.

Mud tubes

Termites construct mud tubes to pass over exposed areas.   These serve to conceal the termites, provide the moist environment they need and to protect the termites from their enemies(ants).  Termites will maintain contact with the soil unless there is an above ground source of moisture. 

Subterranean Termite Shelter TubesOccasional, free-standing shelter tubes are built down from the infested wood toward the ground if they are in a protected area, such as a crawl space under a house. Most often mud tubes are built after a colony has become well established, needing to move farther away from the initial shelter tunnel for food.  Workers quickly mobilize to repair damaged mud tubes.

The warm, moist conditions in the nest provide the ideal conditions for microorganisms, particularly fungi to grow.  Fungi is a source of protein and vitamins essential to the termite.   Fecal material in the nest helps to promote the growth of the fungi.

Termites respond to gradual decreases in the autumn temperature by moving downward in the soil, when spring temperatures and moisture are ideal they move upward again.  In structures where warmth and moisture are present in winter months, termites may be present the year round.


Subterranean termites prefer decayed wood over sound wood, working in the wood facilitates decay by increasing the moisture content.  Often termite damage is associated with decaying wood.  Subterranean termites can consume wood at approximately the rate of 2 to 3 percent of their body weight each day.  Environmental conditions, the size of the termite and size of the colony affect how much they eat.

Communication of Subterranean Termites


Subterranean Termites are social insects with a caste system, communication is needed to maintain efficient social integration and division of labor.  A chemical pheromone is a means of communication among termites.  Each colony develops its own characteristic odor and any intruder be it a termite from another colony, an ant, or any other natural enemy is instantly recognized and soldier termites attack and kill the intruder.   Any damage to the tunnels is immediately repaired by the workers.

Worker termites continually forage for new sources of food, when they find a source of food they recruit others to that food source by laying a pheromone trail for others to follow. As more foragers find the food source and return to the colony the more intense the pheromone trail becomes.


Another means of communication is sound.  Soldier and workers will bang their heads rapidly on the surface of the mud tunnels or wood galleries alerting the colony of a disturbance, the vibration is perceived by the rest of the colony and will join in the banging activity.  This mobilizes the colony’s defenses just as the alarm pheromones do.


Trophallaxis it the transferring of liquids from one nest mate to another by regurgitation or anal feeding.  It is important for the transfer of nutrition as well as passing on pheromones and other chemicals for communication among social insects.  It permits the efficient use of nutrients within the colony, enhances recognition of colony members, distributes chemicals for caste regulation, and transfers cellulose-digesting protozoans needed for digestion of food. 

This regulates the proportion of the castes in the colony.  If high levels of soldier-produced chemicals are detected the colony may react by killing some of the soldiers thus restoring balance to the colony caste system.  Knowing this information has helped Pest Control Professionals develop treatments for eliminating termites.

Western Subterranean Termites

Reticulitermes Hesperus Banks

Found East of the Cascade Mountains they feed on wood and other cellulose debris.  Carpenter Ants and Termites cause a considerable amount of damage to homes in the Pacific Northwest.  Nests of the Western Subterranean termite can be as deep as 10 to 20 ft.  Their nests are found in decaying wood or other cellulose debris, buried in the dirt or stumps and logs.  

They can gain entrance to a home through a porch, through joints in slab foundations, frost cracks, and areas around plumbing, moisture damaged wood is not essential for an infestation.  Any wood that is in contact with the wood is susceptible to infestation. Occasionally building mud tubes over foundations to the wood above is another possible source of infestation.  It is a slow developing species, with the flight of reproductives not usually occurring from new colonies until after the fourth year.

These are the termites found in Portland and the surrounding area as well to Astoria and down the coastline.  Chemical treatments are meant to create a barrier between the nest and the house.  Other treatments include baits that contain a chemical treatment that is meant to be carried back and spread throughout the nest. 

Many products used to treat termites are for licensed professionals only, treatments are complicated and labor intensive.

It is recommended that a Pest Control Professional be contacted for treatment.

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