Termites cause over $ 5 billion damage in U.S. homes each year. One small termite colony of approximately 60,000 termites can eat a linear foot of a common 2”x4” in just 5 months. In some regions of the United States, Formosan subterranean termite colonies typically number in millions and travel over 100 meter distance.
Subterranean termites causes over 90% of termite damage in the U.S. Colonies can contain several thousands to more than a million foragers. Some termites can chew through lead, plaster or mortar to find and eat wood. Almost 4 million U.S. homes are infested by termites each year.
Termites can be found in every state except Alaska. Termite queens live 15 to 25 years and can lay an egg every 15 seconds. There are thousands of termite species but can simply be divided into two types, non-subterranean (drywood termites and dampwood termites) and subterraneans.
Termites are cold blooded and therefore depend on their surrounding environment for warmth.
Drywood termites infest dry, undecayed wood, including structural lumber as well as dead limbs of native trees and shade orchard trees, utility poles, posts and lumber in storage. From these areas, winged reproductives seasonally migrate to nearby buildings and other structures usually on sunny days during fall months. Drywood termites are most prevalent in Southern California ( including the desert areas ), but also occur along most Coastal Regions and in the Central Valley.
Drywood termites have low moisture requirement and can tolerate dry conditions for prolonged periods. Studies showed that drywood termites are heat/temperature sensitive. They remain entirely above ground and do not connect their nests to the soil. Piles of their fecal pellets, which are distinctive in appearance, may be a clue to their presence. The fecal pellets are elongated (about 3/100 inch long) with rounded ends and have six flattened or roundly depressed surfaces separated by six longitudinal ridges. They vary considerably in color, but appear granular and salt and pepper like in color and appearance. Winged adults of western drywood termites are dark brown with smoky black wings and have a reddish brown head and thorax; wing veins are black. These insects are noticeably larger than subterranean termites.
Drywood termite treatment include whole structure application of fumigants or heat and localized or spot treatments of chemicals or treatments that use heat, freezing, microwaves, or electricity. Techniques to prevent infestations of this species include the use of chemicals, pressure treated wood, barriers and resistant woods.
When planning treatment of drywood termites consider whether the whole house structure is to be treated or just localized areas. Difficulty in determining the extent of a drywood termite infestation makes localized/spot treatments difficult to ensure complete control. There also appears to have considerable variations in the effectiveness of various techniques from applicator to applicator. Read your guarantee carefully; you may wish to consider an annual inspection service. Also important is a company’s reputation. Obtain at least 3 vendor bids before you decide. Check the reliability of the vendor by asking for client referrals and check the status of its business license and consumer complaints with the California Structural Pest Control Board in Sacramento and with your local Better Business Bureau. Orange oil, borates and non-repellents are registered to control/exterminate drywood termites.
Subterranean termites require moist environments. To satisfy this need, they usually nest in or near the soil and maintain some connection with the soil through tunnels in wood or through shelter tubes they construct. These shelter tubes are made of soil with bits of wood or plasterboard (drywall). Much of the damage they cause occurs in foundations and structural support wood. Because of the moisture requirements of subterranean termites, they are often found in wood that has wood rot.
The western subterranean termite is the most destructive one found in California. Reproductive winged forms of subterranean termites are dark brown to brownish black, with brownish gray wings. On warm, sunny days following fall or sometimes spring rains, swarms of reproductives may be seen. Soldiers are wingless with white bodies and pale yellow heads. Their long, narrow heads have eyes. Workers are slightly smaller than reproductives, wingless, and have shorter head than soldiers; their color is similar to that of soldiers.
Subterranean termites structures cannot be adequately controlles by fumigation, heat treatment, freezing, or termite electrocution devices because the reproductives and nymphs are concentrated in nests near or below ground level in structures out of reach of these control methods. The primary methods of controlling these termites are the application of insecticides or baiting programs. Insecticides are applied to the soil either in drenches or by injection. Special hazards are involved with applying insecticides the soil around and under buildings and a licensed professional does these procedures best. Some strategies are pre construction, others are post construction treatments. Soil barrier treatments for the entire structure, or use of new technology products for the entire structure may be done. Foundation perimeter treatments are generally considered very efficacious at keeping subterranean termites out of structures. Local treatments are less efficacious. By law, companies must provide you with the following disclosure. “Local treatment is not intended to be an entire structure treatment method. If infestations of wood destroying pests extend and exist beyond the area(s) of local treatment, they may not be exterminated”.
Recently introduced chemicals (imidaloprid and fipronil) are now available that are less toxic to humans and other mammals than the older insecticides (repellent termiticides) but highly toxic to insects. Both of these insecticides are non repellent to termites and have been shown to be effective in killing termites at low dosage under California’s climatic conditions. Bora Care, a borate, is also effective and registered, as preconstruction treatment, against subterraneans. Generally, the most effective insecticides are only available to licensed structural pest control operators.
Sources and References
National Pest Association
Haverty, MI—1976. Termites. Pest Control
44(5) 12-17, 46,47,49.
National Panel Diary 2000
Pest Control Operators of California
UC Davis/UC IPM online
A. Mallis, Handbook of Pest Control, Ninth Edition, GIE Media Inc.