All about termites

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Would it surprise you to learn that termites play a vital role in the ecology of our planet, as well as our own survival? They’re best-known to us for their destructiveness when they take up residence in, well, a residence, and no one wants that, of course. Worldwide, they cause billions of dollars in damage annually, including a billion in the U.S. alone. They’re found nearly everywhere on earth, including the soil in our urban yards. Yet, that’s not a bad thing. You’ll learn why as you read on.

Termites are sometimes called “white ants” because they’re small and live in colonies like ants. But the two aren’t related. Termites, along with cockroaches, are in the order Blattodea and are believed to be evolved from a cockroach-like ancestor. Fossil evidence dates termites back to the age of dinosaurs, the Cretaceous Period, from 65 to 146 million years ago.

Termites are further classified into an infraorder called Isoptera (eye-SOP-ter-uh). Isoptera is from the Greek words iso and ptera for “equal wing,” a reference to the termite’s forewings and hind wings being roughly the same size. The word termite derives from the Latin and Late Latin word termes for “woodworm.”

So far, 3,106 species of termites have been discovered. They’re found nearly everywhere, except the Antarctic, with most living in tropical and subtropical regions. In the U.S., termites are more concentrated in warm areas of the country, but are represented in all states but Alaska.

Why we need termites
Termites live to chow down on wood, or rather cellulose, the main constituent of plants. Some prefer the cellulose in trees (the reason wood structures are appealing), while others like grasses or other plants. Termites have the ability to break down cellulose and that’s one of the reasons they’re beneficial. This has to do with a process called nitrogen fixation.

Nitrogen is crucial in the formation of the amino acids, proteins and DNA needed by plants and animals, including humans, in order to survive. The curious thing is that, while nitrogen makes up 78 percent of the air we breathe, it’s unusable until it’s “fixed” through a complex process that converts it into usable organic compounds. And…most of this fixing is done by specialized bacteria and protozoa living in the gut of termites, where tiny bites of wood and plants are changed into usable nitrogen.

Some of the fixed nitrogen is used by the termites for their own survival. But the rest is expelled in their feces, where they’re churned into the soil for use by plants or are eaten by animals. Humans benefit because our diet includes plants and, for most, animals that eat plants.

Termites are beneficial in other ways, too. They’re prey for wildlife and, in some countries, humans eat them, too. Also, the bodies of termites that die by other means provide nutrients to scavengers and to the soil for plant growth.

Physical description
Termites range in size from 0.16 to 0.59 inch (4 to 15 mm), depending on the species. They have three main body parts: head, thorax and abdomen. Their head has two short threadlike or beadlike antennae and strong, chewing mouthparts for biting seeds, wood and leaves.

Soldier and worker termites of most species are blind and wingless. Wings, when present, are longer than the body and at rest lay flat above the abdomen. Reproductive termites have two pair of wings attached to the last two thoracic segments. Termites lack ears, but they can sense vibrations. Their sense of smell is excellent and they communicate with each other by excreting pheromone-scented trails, touching and grooming each other. They also can sense other odors. They have no taste buds, but are able to distinguish between types of wood. Termites have three pairs of legs, which are attached to the thorax.

Their abdomen contains the respiratory, circulatory, digestive and reproductive systems. The digestive system contains symbiotic bacteria and protozoans that have the ability to break down cellulose into components that can be digested.

Social structure
Termites are called social insects. Like honeybees and social ants, they live in structured colonies and each member has a role to play. A colony may have many thousands, even millions, of related members.

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Formosan Subterranean Termites, Coptotermes formosanus. Worker at top, soldier below. (photo: Gerald J. Lenhard, USDA / EOL; cc by 3.0)

Termites are differentiated physically and by role into one of several castes — queen, king, swarmers, soldiers and workers. Some species don’t have workers; in their case the work is performed by nymphs (immature termites).

Most termites are male and female “workers.” They’re whitish in color, maggot-like and wingless. They live hidden within the nest. In most species, they have no eyes, but that doesn’t prevent them from performing as the workhorses of the colony, the ones that destroy wood and perform other chores. As they eat wood, tunnels are created, eventually riddling the wood so thoroughly that a log may look solid externally but collapse under slight pressure. Workers also must locate food, consume it, feed and groom all other castes and the termite young, repair nests, build shelter tubes and even help defend the colony.

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Formosan Subterranean Termite swarmers. (photo: USDA / Wiki; PD)

“Soldiers” are the male and female defenders of the colony. They’re wingless, blind, sexually immature and have a large head that distinguishes them from workers. They usually have large, powerful jaws (mandibles). Soldiers provide the first line of defense against ants and other insects. They probably detect danger through touch and chemical means. Soldiers defend their colony by rushing to fill broken walls and tunnels. They use their head and jaws to fight predators.

The queen and king are darker in coloration than others in the colony and look much alike, except he is slightly smaller than she. “Swarmers” are males and females with compound eyes, dark bodies and two pair of conspicuously veined wings of equal size. They become the queens and kings of new colonies. They can be confused with winged ants, but ants are much larger and have a skinny “waistline” and antennae with “elbows.” Also, the forewings of ants are much larger than the hind wings. Swarmers shed their wings after mating.

Life cycle
Termites undergo incomplete metamorphosis. This means they proceed from an egg to an immature stage (nymph) to an adult. Nymphs look much like adults. Workers and soldiers are sterile. The queen exists for the sole purpose of laying eggs — that’s all she does day after day! Most of her abdomen is filled with eggs (see photo).The king’s role is to keep the queen supplied with sperm. In a large colony there may be more than one queen and king, with each pair living in their own area.

Fertile queen termite with workers and soldiers, Nasutitermes exitiosus. (photo: CSIRO; cc by 3.0)

Fertile queen termite with workers and soldiers, Nasutitermes exitiosus. (photo: CSIRO; cc by 3.0)

Workers can live up to four years, undergoing several molts, while the queen may live for a decade or more.

Termites destined to become swarmers progress through several molts while in their nymphal stage and ultimately become sexually mature adults with functional wings.

Swarmers leave the nest to start new colonies. On a warm day, they’ll leave their old colony and join thousands of swarmers of the same species from other colonies. As soon as a female accepts a mate, both insects shed their wings and together look for suitable soft wood and begin excavating a tunnel. They’re now the queen and king of what will become a new colony. In a chamber they fashion at the end of the tunnel, the queen lays a few eggs and she and the king care for them and their young until there are enough workers to take over for them.

Studies have shown that some queens can reproduce both sexually and asexually. The asexually produced babies have no genes in common with the king. They become “secondary queens,” mate with the king and produce broods unrelated to the primary queen, which prevents inbreeding within the colony.

Food sources
Termites feed on the cellulose in wood, in dead plant material in the soil and leaf litter, and in animal dung.

Distribution
There are four types of termites: drywood, subterranean, dampwood and mound builders. The first three groups can be found in the U.S. Warmer states typically have the most species and the largest populations. Subterranean termites are found in every state except Alaska. Drywood and subterranean termites are found in the Midwest. Dampwood termites live mostly in California and the Pacific Northwest. As their name suggests, they live in and feed on damp wood lying on the forest floor. Drywood termites don’t need soil or moisture to survive; they live about everywhere, even deserts if there’s dead wood available. Subterranean termites live in the soil, sometimes several feet down.

Where to find them
Some species of termites living in Africa and other warm regions of the world live in mounds they build up 25 feet or more in height! No problem finding them. Here in the states, though, termites live in less palatial, less noticeable circumstances. Drywood termites live aboveground, so look inside dead branches or logs. Even a stack of flattened cardboard boxes can be attractive to termites since these items are made from wood. Sometimes you can spot a colony by piles of tiny, salt-and-pepper-looking fecal pellets dropped outside an entrance to their lodging.

Subterranean termites live in or near the soil, where there’s a moist environment. They tunnel up to the surface to feed on wood and move about through “shelter tubes” they construct of soil and bits of wood glued together with their saliva and other secretions. Look for these runways, smaller than the width of a pencil, on the outside of dead wood and wood structures. Sometimes they’re even stuck to a concrete foundation, serving as a covered highway, as it were, from the soil up to the wooden part of a structure.

Isoptera families
There are four families of termites in North America.

Hodotermitidae (ho-do-ter-MIT-uh-dee) — Rotten-wood termites
They nest in dead wood. Unlike other families, they may live in wood that doesn’t have contact with the ground, so long as it has some moisture. Three species.

Kalotermitidae (cowl-oh-ter-MIT-uh-dee) — Dry-wood and damp-wood termites
Depending on the species, they nest aboveground in either damp or dry wood. They excavate extensively. Dry-wood species will attack structures. Seventeen species.

Rhinotermitidae (rye-no-ter-MIT-uh-dee) — Subterranean termites
They nest from one to several feet belowground and surface to feed on wood — mostly dead stumps and fallen trees. Nine species.

Termitidae – (ter-MIT-uh-dee) Higher termites
Inhabitants mostly of dry regions, they live in the ground. Called “higher” because they have bacteria living in their digestive system. This distinguishes them from “lower” termites, which have protozoa. They feed on wood, plant litter or dung. Fifteen species.

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