Western Drywood Termite, Incisitermes minor

The western drywood termite (Incisitermes minor) is a species of termite that is can be found in western areas of North America. Its native range includes northern areas of Mexico and western areas of the United States, but it has also been found in eastern areas of the United States, Japan, China, and Hawaii. This species prefers to reside in Mediterranean climates that are arid, although it will live in other climates, and can often be found in California oak woodlands in many types of trees like cottonwoods, oaks, and willows. It is also found near human settlements inhabiting plants like alder, ash, walnut, and rose plants. In urban areas, it can infest walls, furniture, and flooring, including tatami in Japan.

The western drywood termite varies in appearance depending on what type of member it is in its colony. Alates or swarmers, which can be male or female, are dark brown in color with an orange head and reach an average length of about .3 inches. Soldiers are larger than alates, reaching an average length of .4 inches and have a broad red head with distinctive black mandibles and large third segment. Pseudergates, also known as workers in the Termitidae family, are capable of changing into male or female alates by moulting, unlike workers of other insect species.

The western drywood termite resides in colonies, which can be found by noting the piles of dried feces known as frass and can hold and average of two thousand to three thousand individuals, although larger colonies have been recorded. Swarms typically emerge from nests during the fall months, but they can occur during the spring and summer months in warmer areas of the species’ range. When a swarm lands, individuals will pull of their wings and crawl around on the ground. Males and females may encounter one another during this time, after which suitable partners will court each other by performing rituals like running together. The pair, which mates for life, then searches for a suitable place to start a new colony.

After a few months of inactivity, the king and queen will breed and lay eggs, which develop from egg to mature adult in about one year. The female will continue to lay eggs throughout her life but will lay the most eggs when she is ten to twelve years old. Immature adults will begin to maintain the nest as soon as they are able to. When the queen is at her reproducing peak, the colony contains about 1,700 individuals that are mostly young adults, although one other female may be present and breeding as well.

The western drywood termite is a highly damaging species, destroying wood structures and trees along the coastline. Although it is more common in its natural habitat, it is increasing in number and expanding its range. This expansion is not directly caused by the termite itself but by travelers who introduce them to new areas, especially those using ships. In human populated areas, this species has been terminated in a number of ways including pesticides. Natural efforts have been used successfully including electric shock, microwave emitting devices, and hot air. If an infestation is not large, the infested wood can be removed before any more damage is done.

Image Caption: Incisitermes minor, USA. Credit: Whitney Cranshaw/Wikipedia (CC BY 3.0)