Winged subterranean termite reproductives emerging from the soil. Photo: Ruth Troetschler
Have you been thinking about termites lately? Perhaps you noticed a flight of subterranean termites on the first sunny day after the October soaking rain, or heard the persistent radio ads pushing Orange Oil as the new safe way to eliminate termites, and wondered if that claim could be true.
Most of us shudder when we discover that our home is termite infested. We may even have visions of the building collapsing! And no wonder. Termites and their protozoa allies are major recyclers of dead wood. Obviously since we use wood to build our houses, termites are a threat. Do not panic, however. It takes many years for termites to threaten a structure.
I frequently get calls from people looking for the "best way to eliminate termites." Most callers want to avoid tenting and fumigation with Vikane. Fortunately we can avoid that unfavorite method, but termite control is never easy.
According to the California Department of Consumer Affairs only two methods are effective for whole-house termite eradication: fumigation and heat. Heat can kill termites. The ThermaPureHeat® process uses big heaters to heat the wood to lethal temperatures. (This method also controls mold, bedbugs, and fungal rot.) I checked www.thermapure.com and located a Santa Clara company, Alliance Environmental Group offering this service.
Spot Treatment Methods
Spot treatment methods affect termites that are accessible and localized. Infested wood can be replaced. Orange oil (with low-toxic active ingredient d-limonene) is injected into termite galleries to kill only in targeted areas. Injection of B.I.O. BLAST 650 (Bioblast) into the galleries, will allow Verticillium lecanii fungus to penetrate and eventually eradicate the colony. The electro-gun® requires drilling to reach termite galleries and kill via electric current. The microwave method kills termites in the walls using microwaves. According to an excellent article by Karen Lindell in the Los Angeles Times, this method is best used for small spot treatments.
Subterranean termites can be controlled in six or more weeks by baits available to pest control operators, and the process is environmentally safer than other methods. One toxicant is hydramethylnon a moderately toxic slow-acting pesticide. Other baits containing the fungal disease, V. lecanii, are used in a bait station containing Bioblast. Soil pesticide barriers are designed to prevent subterranean termite access to the structure, but they do allow movement of toxics into the water supply and household air.
At a season that is typical of each species, winged termite reproductives come boiling out of holes in soil or wood. Subterranean termites swarm on the first sunny day after the first soaking autumn rain. Other termite species swarm at dusk so their movements are less obvious, but if you find winged termites inside your house, take notice. These wings readily fall off and these dark newly wingless termite reproductives run around in pairs looking for suitable wood to start a new colony. Since subterranean termites nest underground, they tunnel primarily into wood scraps or wooden posts which directly touch the soil. They also move along crevices or construct clay tubes to reach above-ground wood. Drywood termites require neither external moisture nor soil contact and their presence can go unsuspected for many years, but their diagnostic hexagonal frass can pile up as minute little spheres below "kick holes."
The following tips will help prevent termites and expensive repairs or fumigation.
• Paint exposed wood, especially the ends of rafters, porches, and decks;
• Keep soil away from the foundation;
• Remove scrap-wood from under the house;
• Ensure that sprinklers do not splash the siding; and
• Remove limbs which overhang the roof so dead branches containing dry-wood cannot reach the roof will prevent termites from flourishing.
If you maintain wood-free dry soil beneath your house, keep garden soil at least six inches away from wood siding, and check the foundation annually to detect and destroy transport tubes, most subterranean termites will be unable to colonize your home.
If you have a problem with a pest control company, visit www.pestboard.ca.gov
Ruth Troetschler chairs the Chapter's Pesticide Committee.