Termites: Identification, Behavior, and Damage Control

Termite

Introduction to Termite

Termite, a small insect. Termites are sometimes called "white ants'' because of their slight resemblance to ants and because they live in colonies as ants do. However, they belong to a different order of insects. Termites are widely distributed around the world, primarily in the tropics, but also in temperate regions. Most termites eat wood and wood products, destroying trees, wooden structures, and paper.

Most termites eat wood and wood products.

Description

There are about 2,000 species of termites. Differences in body structure are greater between castes of each colony than between members of the various species. Usually, there are three basic castes—reproductives, workers, and soldiers—that carry out the colony's tasks. In some species there is only one caste of reproductives, the primary re-productives, consisting of a queen and a king. In others there is a secondary caste of reproductives, and in still others a third. These secondary and tertiary reproductives sometimes replace the king or queen if the primary reproductives die.

The termite has a hard head with chewing mouthparts. The rest of its body is soft. Its thorax is joined to its abdomen by a broad "waist'' instead of by a slender stalk as is the ant's, and its antennae are not elbowed as are ant antennae.

Termite nymphs (young) go through several stages of development. Only the primary reproductives reach maturity, the other castes retaining certain immature characteristics.

Workers and Soldiers

Workers and soldiers are structurally either male or female, but they are usually sterile. The worker termite is wingless. It is ordinarily pale white and from 1/4 to 1/2 inch (6 to 13 mm) long. Most species have no eyes. In some species, the workers do not develop beyond the nymph stage.

Soldier termites are usually about 3/4 inch (19 mm) long. Their heads and jaws are larger than those of workers. Soldiers of some species have nozzle-like projections through which they eject a sticky, offensive liquid to repel enemies. These soldiers are called nasutes (Latin for "large-nosed''). Soldiers are usually wingless, but some have small, underdeveloped wings.

Reproductives

Most primary reproductives are tan, dark brown, or black. A termite queen is larger than other members of the colony. When swollen with eggs, queens of tropical species may be two inches (5 cm) long, a hundred times as large in volume as the king, and several hundred times as large in volume as the workers. The egg-swollen queen looks almost white except for dark broken bands around her body. In most species, the queen and king each have two pairs of wings that are about twice the length of their bodies. After mating, they shed their wings. Secondary and tertiary reproductives are paler than the queen and king, and have wing stubs or are wingless.

Habits of Termites

What Termites Eat

Although woody plants and wood products are eaten by most termites, some eat grass, leaf mold, manure, algae, and soil. Some termites cultivate fungi as food for the colony. Wood-eating termites have protozoans (one-celled organisms) in their digestive tracts. The protozoans digest cellulose, a fibrous substance in the wood, breaking it down into substances that are easily absorbed by the termites' digestive system.

Where Termites Live

Termite nests (termitaria)vary greatly from one species of termites to another. Subterranean termites burrow long tunnels in the earth in which they live and from which they invade plants and wooden structures that are in contact with the ground. If they do not have direct access, they build shelter tubes, tubes of mud and body excretions that serve as passageways from their nests to food sources. Shelter tubes prevent outside air from entering the colony, thus keeping it humid and damp; if the colony becomes too dry, the termites die.

Damp-wood termites inhabit chambers in damp, rotting wood or in living woody plants. Dry-wood termites inhabit dry, dead wood, including that used in manmade structures, such as houses and furniture. Both types of wood termites build shelter tubes, using digested wood.

Some tropical termites build nests in trees or on top of the ground. These nests may be of chewed wood, wood debris, or earth. Nests on the ground may be conical, mushroom-shaped, or made up of one or more vertical cylinders. They range in height from 1 to 30 feet (60 cm to 9 m), and the more elaborate ones may be 15 feet (4.5 m) in diameter.

What Is a Termite Tower?

Most species of termites tunnel down, building nests underground or in trees or wood buildings. But some species build up! These master builders live in Africa, Australia, Asia, and South America. Some build towers up to 30 feet (over 9 meters) high.

How do termites build towers? When termites dig, they bring the soil to the surface. They mix their saliva with the soil so that it hardens. The more soil the termites dig, the higher the tower grows.

Termite towers have a special purpose: to warm and cool the nest. Australian compass termites build towers with flat sides that face north and south. The flat sides catch the sun’s rays in the morning and evening to warm the nest. The pointed top deflects the hot noonday sun.

The fungus-growing termites of Africa have towers that are mostly hollow. Hollow towers act like chimneys, letting the hot air rise. Small tunnels down the sides let fresh air in, keeping the queen cool.

How Termites Live

Once or twice a year, well-established colonies produce swarms of winged reproductives which may number in the millions. Many are caught on the wing by birds and bats. The survivors drop to the ground and break off their wings. Males and females, often from different colonies, pair off and start building a nest. Later, they mate and together tend the first small broods of eggs and nymphs.

For several years the colony produces only workers and soldiers. After three or four years, reproductives are produced. The workers tend the reproductives, young, and eggs. They also forage and enlarge the nest. The soldiers guard the nest from small enemies, such as insects, but they are helpless against such large predators as anteaters and chimpanzees. The number of eggs laid by the queen increases through the years until she is producing about 10,000 a day during most of her life. A queen may live for 50 years. Secondary and tertiary reproductives develop from nymphs, usually after the death of one or both of the primary reproductives. In certain species, some soldiers lay eggs.

Economic Effects and Control

Effects of Termites

Termites are known in temperate climates chiefly by the damage they do to buildings, furniture, books, and certain fabrics. Termites are nevertheless beneficial to man. They increase the soil's productivity by loosening and fertilizing it, making it more water-absorbent, and turning plant material into humus.

In the United States, the greatest amount of damage is caused by subterranean and dry-wood termites. Subterranean termites are found mainly from Massachusetts south to the Gulf states and in coastal California. In the United States, dry-wood termites are found in isolated areas along the southern Atlantic coast, the coast of the Gulf of Mexico, the Mexican border, and the Pacific Coast.

Control

The U.S. Department of Agriculture emphasizes the importance of preventive measures, since it is extremely difficult to get rid of termites once they have infested a wooden structure. Among recommended measures against subterranean termites are chemical treatment of the soil of building sites, use of foundation materials other than wood, and use of chemically treated or naturally termite-repellent wood for woodwork that must come in contact with soil. Chemicals that occur naturally in the heartwood of such trees as California redwoods, longleaf pines, camphor trees, and teaks make these heart-woods to some degree repellent to termites.

Shields of noncorrosive metals such as copper and galvanized iron help prevent infestations by subterranean termites. The shields serve to provide a barrier between hollow masonry foundations and the wooden parts of a building.

To prevent dry-wood termite infestation, construction materials should be termite-resistant, and all openings into the building should be screened. Regular inspection of buildings is recommended.

Services of a professional exterminator are usually necessary when termites have infested a structure. Replacing damaged woodwork and treating undamaged wood with chemicals are effective measures. Fumigation is sometimes used to kill dry-wood termites. Termites in furniture can be killed by heating the furniture in special kilns at a temperature of about 150° F. (66° C.) for a few hours, or by exposing it to a temperature of 30° F. (-1° C.) or less for several days.

Termites make up the order Isoptera. In the United States, the common genera of destructive termites are: subterranean, Reticulitermes; drywood, Kalotermes; damp-wood, Zootermopsis.