Dampwood termites eat across the grain, consuming both spring and summer wood. By doing this, they make a series of chambers/galleries connected by tunnels whose walls are smooth as if finely sandpapered. There is no soil in the galleries, but if conditions are extremely damp, the fecal pellets will stick to the gallery walls and/or form clumps or paste. If conditions are dry, the fecal pellets accumulate at the bottom of the galleries or are expelled the same way as drywood termites do. They use their fecal pellets to seal off galleries or wood, similar to the way subterraneans use soil.
Swarming occurs at dusk or at night, and the swarmers are attracted to lights. The time of year varies with the termite family involved. Pacific Dampwood swarms mainly in August-October.
Control consists of elimination of the moisture source and all wood-to-ground contact. Infested wood should be replaced or treated. Local treatment of the soil and/or wood may be desirable with appropriately-labeled pesticides/termiticides.
WESTERN DRYWOOD TERMITES
Drywood termites eat across the wood grain and make chambers and/or galleries connected by tunnels. Their gallery and tunnel walls are velvety smooth, and no soil is present. Usually there are fecal pellets present which are hard, less than 1/32” long, elongate-oval with rounded ends, and have 6 concave sides. Signs of infestation include swarmers, shed wings, piles of pellets, termite plugs which seal all openings in infested wood, and surface blisters caused by older enlarged galleries very close to the wood surface. Damage to wood occurs slowly. Under optimal conditions of 80-90 degrees and 50% relative humidity, it has been estimated that one drywood termite eats about 0.59mg of wood per day. Therefore, a colony of 1,000 mature nymphs would consume about ½ pound of wood in a year. Be aware that it would take a drywood colony about 7+ years to reach this size. Swarmers often reinfest the same structure. Annual damage and treatment costs in California and Arizona are estimated (2006) to be $250 million.
Swarming drywood termites fly into structures and infest wood directly. When swarming, they often reinfest the same structure. They typically first invest exposed wood such as window/door frames, trim, eaves, attics, etc.
Since infestation is direct and not via the ground, the most successful methods of control are fumigation, or local treatment or replacement of the infested wood. Fumigation is recommended if infestations are widespread and/or difficult to access whereas, local treatment with pesticides or other means is prudent where infestations are isolated and accessible. Localized infestations may be treated via intergallery injection or surface treatment with pesticides which are labeled for these termites.
WESTERN SUBTERRANEAN TERMITE
Subterranean termites eat mostly the spring wood, which they prefer over the harder summer wood. Hence, damaged wood appears to be layered. Sometimes soil is present in the galleries.
Colonies are usually located in the ground. Location is usually below the frost line, but above the water table and rock formations. Mud tubes are built to cross areas of adverse conditions between the colony and food sources. They can enter structures through cracks less than 1/16” wide. However, if a constant source of moisture is available (i.e. leaky pipes), colonies (called secondary colonies) can exist above ground and without ground contact.
Control involves placing a chemical treatment zone and/or an in-ground monitoring-baiting system between the termite colony and the wood of the structure. In addition, all wood-to-soil contact should be eliminated, any wood debris must be removed, and the wood moisture content should be reduced to below 20%. Secondary colonies are controlled by correcting the moisture problem to dry out the moisture-source area. When it is desirable to rapidly reduce the secondary infestation, this can be done by intergallery injection or surface treatment with a pesticide labeled for these termites. Also available are above-ground baiting systems that are placed directly on the infested wood.
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