[Termite Control] Understanding the Biology of Termites

Photo by Gary Alpert, Harvard University, Bugwood.org

An accurate understanding of the biological aspects of termites is helpful in implementing a successful termite management program and in developing new termite management tactics.

Termites are ancient insects that date back about 180 million years; they belong to the insect order Isoptera, which means “equal wing.”

Termites usually feed on wood, leaf litter, dead grasses or soil. In general, termites in North America prefer feeding on dead or decaying wood, but they can feed on anything that contains cellulose, such as paper, cardboard, carpet, drywall, thin lead and copper sheeting, plaster, asphalt, flooring, sub-floor, furniture, trim, window frames, etc.

There are about 2,753 termite species in 285 genera worldwide. In the United States, less than 50 species are known. Ecologically, and based on the nesting habits of the specific termite species, termites are classified into four different groups: subterranean, dampwood, drywood and mound-building termites.

Mound-building termites are not found in North America. Subterranean termites live in the soil, or in moist wood, but they need soil to survive; therefore, they construct mud tubes to gain access to food, maintain moisture and protect themselves from predators. Drywood termites do not require contact with the soil. They live in dry wood with low moisture content, while dampwood termites live in decayed wood with high moisture content, and with most species not requiring contact with the soil.
 

Social Insects. Termites are social insects. They live in colonies that contain eggs, larvae (immatures) and three basic castes: workers, soldiers and reproductives. Termite eggs hatch into larvae that are capable of developing into any caste, depending on the time of year, diet and pheromone influences. Workers are the majority of the termites in the colony. They are males or females performing multiple activities, including feeding the colony, digging/excavating, searching for food and water sources, building and maintaining the nest. Soldiers have a bulb-like head with powerful mandibles that help them to carry out their task in defending the colony from different invaders and predators.

Reproductives are divided into two categories: primary reproductives and supplementary/secondary reproductives. Depending on the species, termites produce alates (winged sexually matured males and females) at a particular time of the year, that fly at a certain time of the day and under specific conditions. Alates lose their wings after flying and become dealates (meaning they shed their wings after a mating flight). Dealates dig into a suitable location in the wood or soil (subterranean termites) next to wood, mate and start a new colony. Every new colony initially begins from the primary reproductives, the king and queen, who periodically mate to support the growth of the colony. Depending on the species, queens can lay thousands of eggs per day and may live for up to 50 years, while the average life-span of a termite queens is about 15 years.

Neotenic reproductives are developed from different instars with or without wing buds capable of replacing the primary reproductives in a colony when needed. There are three common secondary reproductive forms of termites: 1) brachypterous neotenic, developed from nymphs and have small wing buds; 2) apterous neotenic, developed from workers and have no wings; and 3) pseudergates “false workers,” developed from nymphs that lose their wing buds and revert back to become workers.

The supplementary/secondary reproductives take the responsibility of laying eggs without swarming when the primary reproductives die, become infertile or are removed from the colony. Secondary reproductives also could establish separate new colonies by budding if a huge increase in the parent colony size happens, or after physical destruction of the colony due to floods, droughts or construction. Similar to Pharaoh ants, repellent pesticides also could stimulate a budding behavior in foraging termites.

The author is technical training director for Adam’s Pest Control, Minneapolis, Minn. Contact him via e-mail at meldamir@giemedia.com.