Termites: Isoptera

Termites lead secretive lives hidden in wood, underground, or in specially constructed tubes or nests. They seldom come out in the open, except to mate, but some species routinely search for food above ground. They are social insects that live in colonies with thousands to millions of individuals. Most colonies are made up of different castes (workers, soldiers, kings, and queens) that work together to expand and repair the nest, defend the colony, reproduce, and care for and feed the young.

A long-lived king and queen are usually at the head of each colony. The queen is the only member of the colony capable of laying eggs. Workers make up the majority of the colony's population. They build and repair the nest, hunt for food, and feed and groom other members of the colony. However, among primitive termites, there is no true worker caste. Instead, their wingless young perform the tasks of workers. Soldiers defend the colony from ants and other invaders by snapping their scissorlike jaws at the intruders, chopping them up into little bits. Others have very small mouthparts, but their heads are packed with special glands that produce sticky and poisonous fluids. Some of these termite soldiers have pointed heads that are used as spray nozzles to direct a foul smelling, sticky glue at their attackers, gumming up their legs and antennae.

Termites rely on pheromones (FEHR-uh-mohns), special chemicals released from their bodies, to find one another and to communicate. For example, workers and soldiers have glands underneath the thorax that produce pheromones that compel others nearby to help repair damages nest walls. Species that tunnel through the soil create chemical trails underground so that their nest mates can follow them to food.

Termites spend a lot of time grooming, nibbling, and licking each other with their mouthparts. They also drink fluids from the tip of one another's abdomens, so they can pass along the microscopic organisms they need to help digest plant materials. Primitive termites live in or near their food source. The most familiar wood-feeding species nest in tunnels chewed in dead logs, stumps, and timbers. Some desert species live in the soil or under a protective papery coating that they build on the outside of the dead branches and trunks of desert plants. Other termites build their nests away from any food source. Their nests are constructed entirely underground, beneath rocks, partially above ground, or completely on the surface. Underground nests are usually made up of chambers or layers of tunnels, called galleries. The walls of the chambers and galleries are plastered with the hardened waste material of termites.

Species living in the open grasslands of Africa, Australia, and South America build cathedrallike mound nests on the surface, using mostly clay and their own waste droppings mixed with saliva as building materials. Some of these mounds are truly the skyscrapers of the insect world, reaching a height of 36 feet (10.9 meters) or more. The inside of these towering structures are filled with chambers, chimneys, and ventilation shafts that function as air conditioning to maintain fairly constant temperatures inside, no matter what the temperature is outside. With their walls almost as hard as concrete, these mounds are truly monuments, lasting for decades or even centuries.

In the tropics termites sometimes attach their lumpy or mushroom-shaped nests to tree trunks or high up on tree limbs. These nests are often linked to the ground by a series of tubelike runways. The materials used to make these mounds and tubes depend on the diet of the particular termite. Typically, they are made from chewed-up bits of plants, soil, and termite droppings, all mixed with saliva. Once dried, the nest walls feel and look like very coarse paper.

Each spring and summer thousands of winged kings and queens take to the air. They soon land, shed their wings, and begin the search for a mate from another colony. Some queens produce a pheromone to attract males. In some species, a pair of termites runs rapidly over the ground in a zigzag pattern during courtship, with the queen leading the way and the king following close behind. After courtship, the king and queen search together for a nesting site, usually in the soil or in a crevice (KREH-vuhs) or hole in wood. After clearing a small chamber and sealing themselves inside, they mate. All termites, whether they are male or female, develop from fertilized (FUR-teh-lyzed) eggs.

In other termite species, new colonies form by a process known as budding. Their sprawling colonies simply keep expanding into new territory, with new kings and queens moving to the edges of the continually expanding nest to start their own colonies. Their workers and soldiers mix freely with those of the original colony.

The king and queen tend to the first batch of young and actively join in nest building and other duties, but these tasks are taken over by the young termites as they mature. Young termites look like the adults when they hatch. They molt, or shed their external skeletons, several times before reaching adulthood, and they may or may not develop wings. Eventually, they and future generations take over all of the duties of the nest. Soon the queen's only job is to lay eggs. Some queens live as long as twenty years and lay millions of eggs during their lifetimes. In mature colonies, if the king or queen should die, he or she is quickly replaced by another king or queen already developing in the nest.