There are close to 2500 species of termites described worldwide. If you weighed all of the termites, they would weigh twice as much as all of the humans on the planet. There are over 50 species in the United States, but only a few species of subterranean termites and drywood termites are serious pests.
Drywood termites (Kalotermidae)
Drywood termites do not need soil contact. They live in dry, sound wood, usually near the surface. They get what moisture they require from the wood they feed on and from the water formed during the digestion of that wood. Drywood swarmers generally enter your home at night through an unscreened attic or foundation vents or through cracks and crevices between exposed wood. Drywood termites are most commonly recognized by their distinctive fecal pellets (piles) that are often the color of the wood they are feeding upon. The fecal pellets are kicked out of the wood by the nymphs (workers) through “kick holes“ that are visible. The western drywood termites (Incisitermes minor) are found in much of California where it is a major pest. It is also found in Arizona, Utah, and New Mexico.
Subterranean termites (Rhinotermitidae)
Subterranean termites are social insects with very large colonies. They consist of a queen, sexual reproductives, workers and soldiers. The workers are grayish or white and wingless. They are the ones in the colony that forage for food. They also groom the queens, eggs, nymphs, and soldiers and build the nest. Workers are the ones who do the damage to the wood. The termite workers have a mass of unique genera and species of oxymonad, trichomonad, and hypermastigote flagellates (protozoa) in their lower digestive tract and it is these protozoans that enable the termites to digest wood.
There are two species of subterranean termites in California. The Western subterranean termites (Reticulitermes hesperus) are found from British Colombia south to western Mexico and is very common along the Pacific coastal areas. It occurs as far east as Idaho and Nevada. Their colonies can reach several hundred thousand individuals and the colony has to be about three years old before they can swarm. They do extensive damage and will attack fence posts, utility poles, and wood products on the ground, and living plants and trees. The Arid land subterranean termites (Reticulitermes tibialis) are found in arid desert areas and higher elevations and ranges from Oregon and Montana, south to Mexico, and eastward to Missouri, Arkansas, and Texas. It is the least destructive of the termites, although it can cause considerable damage in some situations.
Formosan subterranean termites (Coptotermes formosanus) are larger than our native subterranean termites. They were introduced from Asia on ships. They are very destructive and attack all kinds of wood and cellulose products. They will also attack living plants when moisture is not available anywhere else. They have been known to hollow a building wall in three months in Hawaii. They can also attack and become established on wooden ship hulls and in this way, be transported from port to port. Evidence of their presence are channels between pieces of wood. Passageways or dirt-colored tubes are usually built on foundations. They do not have to maintain ground contact if adequate moisture is available, so a normal subterranean treatment may not be effective. Colonies are large and contain up to a million individuals. Formosan termites are established in Hawaii and have been introduced in Texas, Louisiana, and South Carolina, and have had isolated cases found in California.