Termites - May 30, 2001
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
Termites have been around for over 250 million years. These social insects occupy colonies located in the soil of in wood. Most feed on cellulose from wood, other dead plant parts, or paper. They are distributed worldwide with about 2,500 known species. Fifty termite species are known to occur in the United States, 17 of these occur in Arizona of which 7 are considered economically important due to the damage they cause. Entomologists place termites into three broad groups based on their habits: subterranean, dry-wood and damp-wood.
In their defense, we must appreciate termites for what they do in nature. They feed on dead wood and other plant materials, breaking them down to become part of the soil. The result is essential plant nutrients and organic matter that, in turn, supports plant growth. However, when they begin to "recycle" human dwellings, we take it personally and usually respond by trying to aggressively control them. It is necessary to understand the biology of termites in order to control them successfully. As with any pest control effort, you must correctly identify the pest.
A single colony contains individual insects that look very different from one another. The form of termite most commonly found by homeowners is the winged reproductive. These winged forms may be confused with winged ants, but once they are examined closely, some distinct differences appear. Termites have two pairs of wings that are the same size and shape, with many veins held flat over their back. The wings of ants, on the other hand, are not equal in size (the back wings of ants are smaller) and the wings have relatively few veins.
Worker termites are light-colored insects with a broad connection between the thorax and abdomen. Their antennae are straight and resemble a chain of beads. There are two short appendages at the end of the abdomen called "cerci". Conversely, worker ants are usually dark-colored, considerably constricted in the middle, and their antennae have a distinct bend or elbow.
Subterranean termites derive their name from the fact that they must be in constant contact with the soil as a source of moisture. In order to move into wood sources above the ground, they construct long tubes of soil, soft fecal matter, and wood chips. Subterranean termites also construct swarming tubes during the rainy or monsoon season, which protect the reproductive forms on their way to the mating flight. These tubes are often used as evidence of termite infestation.
To prevent subterranean termites in older homes, insecticides should be applied to soil around the foundation and around pillars and beneath the slab where cracks may have occurred. A homeowner may apply these treatments, but it does require special equipment. After the barrier is applied, care should be taken to maintain it. If the barrier is disturbed by construction, or if rainwater washes the treated soil away, termites may be able to gain access to wood within the home. Currently most new homes are treated with a pretreatment barrier that is guaranteed to protect a home from subterranean termites for five years.
Dry-wood termites, as their name suggests, are capable of infesting dry wood that is not in contact with the ground. They do not construct long tunnels to the soil surface, making infestations harder to detect. One sign of dry-wood termite infestations is the presence of hard, dry fecal pellets that resemble sawdust. Under the microscope the pellets have pronounced dimples giving them the appearance of dry corn kernels. Dry-wood termites are larger than subterranean termites (winged reproductives are 7-11 mm long), and they construct larger galleries. To prevent dry-wood termites, keep all vents and openings covered, and seal all cracks. Drywood infestations are generally easiest to control by removing the infested wood and replacing it with new wood.
Damp-wood termites are found in the sound dead wood that is moist. These termites produce fecal pellets that resemble dry-wood pellets, but are larger and are generally moist. They nest in soil and come to wood for food. The tube-building species that occurs in Arizona does not harm buildings or wood structures.
The key to preventing structural damage is early detection. Homeowners should inspect their homes at least once or twice a year for signs of termite activity. These include: mud tubes, holes in wood that appeared since last inspection, pellets or sawdust, piles of wings, or swarming insects. If there are any indications of infestation, then you may consider requesting a professional inspection (there will be a fee for this service).
Remember, however, that inspectors are only human, and some infestations may be overlooked if they are located in an inaccessible area. To increase their chances of success, some firms employ termite-detecting dogs to sniff out termites, or use sophisticated equipment such as fiber optic scopes or ultrasonic listening devices. If an infestation is found, the control method of choice will depend on the type of termite involved and it's location.
The University of Arizona Cooperative Extension has publications and information on other structural pests. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/.
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Last Updated: March 15, 2001
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