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Termites
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The following is an excerpt from the Bohart Museum Society Newsletter: Termites Ecologically, termites play an important role in the world as recyclers of dead and decaying wood. However, they are also destructive pests of building materials and cost around $1 billion each year in the U.S. for treatment and repairs. There are at least 45 species of termites in this country - not all of them native - and 30 of these are considered pests. Most termites can be broadly classified as either drywood or subterranean. Drywood termites nest and spend most of their lifecycle within wood. Subterranean termites live and nest in the ground, and forage above ground. In general, subterranean termites cause more damage to homes and other structures than drywood termites because their colonies can get much larger (some termite colonies can have as many as 7 million foragers). A colony or nest of subterranean termites may be up to 18-20 feet below the soil surface to protect it from extreme weather conditions. The most economically important subterranean termite in California is Recticulitermes flavipes. An even more destructive termite, the Formosan termite Cryptotermes formosanus has been getting a lot of attention lately, but it has only been established in the southern states. Termites start life as eggs, which hatch into small larvae. The larvae develop through 6 or 7 stages, with each stage lasting from 2 weeks to 2 months. Termites are relatively long-lived for insects, with average life spans of 3 to 5 years. A mature termite colony has reproductives (king and queen), soldiers, and workers. Full-grown workers are soft-bodied, wingless, blind and creamy white. Soldiers also have light-colored bodies, but their heads and mandibles are usually dark brown or black. Termite colonies have both a queen and a king. As young adults, queens and kings have wings, but once the colony is established they will shed their wings. If a queen or king dies, a particular type of worker may become a replacement queen or king. Control of Termites Suppressing termite activity in or around one's home is not an easy task. Because they live in large numbers deep underground it is difficult to eradicate an entire colony. Baits. Some products act as baits, to attract termites to a slow-acting poison. This method can be effective because worker termites regurgitate digested food in order to feed soldiers and reproductives - this is called trophallaxis - and so the poisons can be passed on from a few workers to the entire colony. The poison must be slow acting because termites will wall off contaminated food sources. Many pest control companies use perimeter baits that are placed in a ring or grid around the property. The percentage attack rate on perimeter baits are low (<10%), however once baits are found, feeding is persistent. Termite activity is seasonal, so it is best to bait termites when they are most active, especially in the late spring and early summer when they are producing reproductives. Foraging also wanes during very hot weather or persistent rains. Baiting takes 2 to 3 months before results are noticeable. One can make homemade baits by burying hollow wooden stakes, with the top end stuffed with cork or cardboard. Termite feeding can be monitored just by removing the stuffing and looking for evidence of termite damage. If termites are found, corrugated cardboard is inserted into the stake, leaving about an inch of the cardboard exposed above the stake. This cardboard, a favorite food of termites, will act to direct the termites up through the stake to the bait, which is placed at the top of the stake. The bait is made up of treated cardboard (cardboard soaked in a 0.1% boric acid solution) rolled into a short length of PVC pipe. This pipe is then capped (with a PVC cap) and placed on top of the stake. Chemical Treatments. Termites can also be controlled by chemical applications to soil around or under wooden structures, to the building materials themselves, or by fumigation. Chemical treatment of the soil for subterranean termites must be done wherever soil is in contact with wood. In some cases this means that treatment must be done beneath the foundation of a structure. It is also possible to purchase pre-treated lumber to prevent infestation. Fumigation is a treatment most often applied to drywood termites because the entire colony lives within the wood itself, not underground. Other Methods. There are other methods to control termites that are currently being researched. One of these is the release of a fungus that is a natural enemy of termites. Another is the use of a chemical that inhibits the production of cuticle by the termites, which prevents molting and growth. It may be that a combination of methods and careful monitoring to detect early infestations are the best means to control termites. Bohart Museum Society Newsletter |
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