Wood Destroying Insects: Termites

Drywood Termites

Drywood termites are social insects that live in colonies. The colonies are composed of kings, queens and soldiers. There is no worker caste as in subterranean colonies. The work is performed by immature termites before they become adults. King and queen termites perform the reproductive functions of the colony. They are light to dark brown and 1/3 to 1 inch in length. Soldiers guard the colony against invaders such as ants. They are white and wingless with large brownish heads and jaws. The nymphs (immatures), which are the most numerous caste, are white and wingless. The soldiers and immatures remain inside the wood at all times.

Termite food consists of cellulose obtained from wood. Protozoa in the termites' digestive tracts convert the cellulose into usable food. Infestations of drywood termites may be found in almost any product containing cellulose. This insect is most commonly found infesting woodwork in buildings and furniture.

Non-subterranean termites remain hidden within the wood or other material on which they feed, so that those actually feeding are seldom seen. 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. Galleries made by the subterranean species follow the grain of the wood and attack only the soft spring wood.

Signs of Infestation

There are several signs of drywood termite infestations. At certain times of the year during daylight hours, king and queen termites emerge from the colonies. The purpose of these flights is to establish new colonies. Peak swarming periods are from September to December in Florida although they may occur to a lesser extent during other months. Winged termites can be distinguished from winged ants because termites have a thick waist whereas ants have a distinctly thin or wasp-like waist. The appearance of winged termites in the home is an indication of probable infestation; however, they may come in from outside. Wings break off shortly after the termites swarm and, because they are attracted to light at this stage, their discarded wings are often found on window sills.

Drywood termites, unlike subterraneans, excrete pellets of partly digested wood. These pellets are straw-colored to reddish-brown and about the size of sand. The pellets are pushed from the galleries and found on surfaces beneath the infested wood. Infestations are most common in the attic or in window frames and sills. A sign of advanced infestation is surface blisters. These termites sometimes tunnel close to the surface giving the wood a blistered appearance. Infestations may be detected by tapping the wood every few inches with the handle of a screwdriver. Damaged wood sounds hollow - a papery rustle sound indicates tunnels just beneath the surface.

Preventive Measures

Used lumber, furniture and other wooden articles, especially from coastal areas in Florida, Georgia, the Carolinas, Alabama, Mississippi, Louisiana and Texas, should be carefully inspected for termite infestations. Drywood termites are also present in New Mexico, Arizona and California. Drywood termites may enter a building through the attic or foundation vents, under or directly through shingles or under eaves. All windows, doors and vents, especially those in the attic, should be screened with 20-mesh screen. Paint gives exposed wood protection against termite entry. Before painting all cracks and crevices should be filled with putty or plastic wood. This should provide protection for about, five years. Commercial pressure- treated wood will give protection for a much longer period and will prevent drywood termite attack. Certain woods are naturally resistant to termite attacks; among these are heart wood of redwood, bald-cypress, mahogany and Spanish cedar; however, these woods will become susceptible after several years of weathering.


Drywood and subterranean termites require completely different control methods; therefore the termites must be correctly identified. If in doubt, take several soldiers, winged specimens or broken-off wings to your County Extension Office. Immatures (workers) are virtually impossible to identify.

If detected in the early stages and damage is localized, a drywood termite colony may be controlled by removing and replacing the damaged wood or by the application of an insecticide. It is very important to carefully inspect all woodwork of the entire building, especially attics, baseboards, window sills, floor joists and furniture for termite pellets and/or damaged wood.

If detected in the early stages and damage is localized, a drywood termite colony may be controlled by removing and replacing the damaged wood or by the application of an insecticide. It is very important to carefully inspect all woodwork of the entire building, especially attics, baseboards, window sills, floor joists and furniture for termite pellets and/or damaged wood.

If the infestation is too extensive and advanced for local treatment, it will be necessary to tent and fumigate the entire building. Although this method is very expensive and leaves no residual protection, it is usually the only alternative when many termite colonies are present. Fumigation can only be performed by a licensed pest management professional.

Fumigant, gases used for structural fumigation are 100% effective when adequate concentrations are maintained within the structure. Proper fumigation will not damage household products.

Formosan Subterranean Termites

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is one of the most destructive termite species in the world today. In the United States, it causes tremendous property damage resulting in enormous treatment and repair costs. It is sometimes referred to as the "Super Termite" because: It has large colonies. The territory of a single colony can be up to 300 feet. It infests a wide variety of structures (including boats and high-rise condominiums). It eats wood at a rapid rate.

The Formosan subterranean termite has the potential to spread throughout the whole state. Young colonies living in potted plants, landscape timbers, or infested trees are easily transported. A good example is given in Louisiana and Georgia where their spread was aided by homeowners who accidently brought termites to their homes by buying infested railroad ties at home and garden shops. Alates (winged reproductives) also can swarm from infested boats into new locations as the boats travel from place to place.

Biology and Habits

In New Jersey, Formosan subterranean termite swarms usually occur from April through July on calm, warm, and humid evenings. Swarms are quite large with up to tens of thousands of alates. The swarmers are attracted to lights and are often found around windows, light fixtures, windowsills, and spider webs in lighted areas. After swarming and landing on the ground, the alates break off their wings and search for a mate. Once a mate is found, the male and female search for a crevice in damp ground or wood, hollow out a small chamber, and crawl inside. The pair, now known as the king and queen, mate and within a few days the queen starts laying eggs. The young, known as larvae, hatch from the eggs and are fed by the king and queen.

A mature colony contains distinct groups called castes. These castes look different from one another and each has a special duty within the colony. The king and queen are the primary reproductives and are responsible for reproduction. If the queen or king dies or the colony becomes large, secondary reproductives may form and begin reproduction. Soldiers defend the colony against predators and other natural enemies. Workers take care of and feed the larvae, reproductives and soldiers, tend the eggs, build and maintain the nest, and search for food. Alate nymphs become alates when they are fully grown.

Formosan subterranean termite colonies are much larger than those of native subterranean termite species. Some have been estimated to have over 8 million individuals compared with about 1 million termites in large native subterranean termite colonies.

Like many other termites, the Formosan subterranean termite feeds on wood and other materials that contain cellulose, such as paper and cardboard. Cellulose is the main structural component of plants. Bacteria and other single-celled organisms live in the termite digestive system and digest cellulose providing nutrition and energy for these termites.

Although they feed mostly on wood, they will eat other cellulose-containing materials such as cardboard and paper. However, they are known to chew through foam insulation boards, thin lead and copper sheeting, plaster, asphalt, and some plastics.

Contrary to popular myth, THEY DO NOT EAT CONCRETE nor can the soldier's defensive fluid dissolve holes in concrete. These rumors continue because Formosan subterranean termites are always digging through the soil. Because of this continuous activity, they are likely to find cracks and crevices in concrete or mortar and gain entry to a structure. This can fool someone into thinking that Formosan subterranean termites can eat through solid concrete.

Subterranean termite species, such as the Formosan subterranean termite, generally live underground. They tunnel through the soil in search of food. Unlike native subterranean termites, Formosan subterranean termites build nests. These are made of carton, a hard material the workers make from soil, chewed wood or plant matter, and their own saliva and feces. Carton nests are quite impressive - a large, rock-like mass constructed by hundreds of thousands or millions of termites.

Although nesting mostly below ground, some Formosan subterranean termite colonies will build above-ground nests that are not connected to the soil. Nests can be made in structures where the temperature does not get too hot or cold and there is plenty of moisture. Sources of moisture include: plumbing, water heater, and roof leaks, condensation from air conditioning units, poor drainage from gutters and flat roofs, seepage and rainfall on boats and ships, porches, balconies, rooftops, etc. with plants or landscaping that are frequently watered.

What to Look For

Large carton nests in trees, attics, wall voids, etc., are obvious signs of an infestation. Sometimes the damage caused by Formosan subterranean termites is not so obvious. Soft spots, damp or moist patches, bulges, and blistered paint or wallpaper in walls, doors, floors, and other areas may indicate termite activity underneath. Probing these areas with a screwdriver may reveal damaged wood, mud, carton, and live termites. Formosan subterranean termite infestations are recognized by the presence of lots of soldiers.

Subterranean termites crawling above ground build mud shelter tubes because they do not like being exposed in the open to light and air. The tubes keep the termites from drying out and shield them from predators and natural enemies. Shelter tubes are often found on walls coming up from the ground or floor. They may also be found sticking out or dropping down to the ground in crawl spaces, under porches or stairways, etc. Tubes and carton may be in places where they are difficult to see such as stucco or plaster cracks, tree holes, tree crotches, etc. You can break the tubes open to check for termites.

Remember that Formosan subterranean termites swarm during the evening from April through July. Keep in mind that swarmers outside around your home could be emerging and flying in from somewhere else. Check carefully around the premises to see if they are coming from your property.


Treating soil with a liquid termiticide creates a chemical barrier beneath the structure. Depending on the chemical, the termites will either avoid tunneling through treated soil or die soon after they come in contact with it. Soil termiticides have been the standard preventive treatment for subterranean termites up until the mid-1990s. Termiticides are applied before the foundation slab of a structure is poured. Under ideal conditions, protection should last from five to seven years; but under less than ideal conditions or because of improper application it can be much less. The slightest break in the protective barrier is all that is needed for termites to reach a structure. They can tunnel through areas in the soil where no termiticide is present. Expansion joints, cracks, and utility and plumbing lines are common termite entry points through a concrete slab. Termiticide breakdown, soil erosion, improper application, and careless construction practices (such as leaving wooden grade stakes in the slab or disturbing treated soil) are several ways that the chemical barrier can be broken.

Post-construction treatment

When infestations occur after a structure has been built, termiticides are applied by one of three methods: rodding, drilling, or trenching. In the first, termiticide is injected directly into the soil at specific intervals around the perimeter of the house and beneath the slab with a rodder, an injection tool with a long, hollow, metal rod with an open tip. Drilling involves making holes through concrete slabs, walkways, patios, walls, and floors in order to treat the soil beneath the slab or inside wall voids. Trenching involves digging a shallow trench (about 6 X 6 inches) around the base of the home, applying termiticide to the trench and the backfill and then refilling the trench.


Baiting systems provide an alternative to liquid termiticides. Developed in the early 1990s, they are also effective against the Formosan subterranean termite. Baiting involves placing bait stations in the soil around the outside of the house. The stations contain small pieces of wood (in some products the stations are installed with both wood and bait) and are checked regularly for termites. When termites are found in a station, the wood is removed and replaced with the bait. The bait is typically a paper-like material that contains a substance that slowly kills the termites. The idea behind baiting is that the termites feed on the bait and get a dose of the active ingredient. Although this does not kill the termites immediately, it gives them enough time to feed the other termites in the colony. Eventually, all the members of the colony are affected. The termites begin dying and the population of the colony is severely reduced or eliminated.

Several different baiting systems are now being used by pest management professionals or are commercially available. Some have insect growth regulators (known as IGRs) as their active ingredient (AI). These are chemical compounds that act like termite hormones and keep the termites from developing normally. Other AIs prevent the termites from getting energy from their food.