Subterranean Termites

The Western subterranean termite, Reticulitermes Hesperus, as its name implies, is found principally in the western part of North America, from British Columbia south to western Mexico and east to Idaho and New Mexico.

R. Hesperus can be distinguished from other subterranean termites by comparing the characteristics of swarmer and soldier castes. The swarmers are approximately 3/8 inch long, including wings, and their bodies are dark brown to black in color. The fontanelle (small pore-like opening on the front of the head) is often inconspicuous. The wings are characteristic of subterranean termites: they have two dark veins on the leading edge of the wing, while the remainder of the veins are relatively clear. The soldier’s head is rectangular in shape and is at least two times longer than it is wide. Other features of the soldier caste include a dorsal fontanelle, cream coloring with the head a little darker, and mandibles without teeth.

Damage caused by this species is very similar to that caused by the eastern subterranean termite, R. flavipes. These species eat springwood and leave the lignin-containing summerwood, making the damaged wood appear to be layered. Typically, soil is found in their galleries.

After swarming, kings and queens pair off, prepare a cell, and then mate within 24 hours of completing the cell. The female produces an average of 10 eggs in the first bath, which develop in 50 to 56 days. There are 4 to 7 instars: the first lasts 14 to 18 days, the second 14 to 18 days, the third 30 days and the fourth about 60 days. Nymphal development normally requires 5 months, and workers may live 3 to 5 years. Normally, swarmers are not produced until the third of fourth year.

Swarming occurs in the spring during daylight hours. In its northern range, swarming is not dependent on rain, whereas in its southern range swarming follows rain. Fall swarms occur in the South and may be very large.

Colonies are usually found in the soil beneath the frost line, but above the water table and bedrock. However, if wood moisture content is 20 percent or more, the colony or its secondary colonies can survive in the wood without maintaining soil contact. Termites construct mud tubes to breach adverse conditions and reach food, and use cracks as small as 1/16 inch to gain access into a structure.

Integrated pest management for termite control begins with a thorough inspection of all accessible areas for evidence of infestation and conducive conditions. Once an infestation is detected, the first remedial step is to remove wood debris and other cellulose-containing material. A minimum gap of 8 inches between soil and any wood in the structure should be established. If the wood moisture content is greater than 15 percent, recommend that the homeowner solve this problem, such as by repairing plumbing leaks or correcting poor drainage.

Be sure to inspect structures for foam insulation that is in contact with soil and the wood in the structure, forming a bridge between these two materials. In these situations, treat the foam as if it were wood in contact with soil.

Establishing a continuous termiticide barrier between the colony and the structure’s wood remains as the major preventive and corrective procedure. To maximize longevity of the treatment, make the application at the highest concentration and volume permitted by the label. If PCOs suspect that colonies exist in the wood, they can treat the wood by injecting a dust or liquid insecticide labeled for this use. Below is an image you can use to help spot if you are experiencing Subterranean Termites.

Learn More About Drywood Termites