Western Drywood Termites - Termite Control Methods

Area of Distribution: The Western drywood termite is found in the southwestern states, as far north as Sacramento, as well as coastal areas, especially the Gulf Coast regions and Florida.

Destructive Nature: The Western drywood termite causes most of the drywood termite damage in the western United States. Colonies can contain several thousand termites. Severe damage may be caused by the presence of multiple-colonies. The drywood termite as the name suggests can survive in timber with a low moisture content.

Drywood termites can be transported in infested furniture, picture frames, and other articles made of timber. The Western drywood termite has been occasionally found in St. George, Utah, Milwaukee, Wisconsin, Cleveland, Ohio, Niagara Falls, New York and other areas, but it has failed to become established in such areas outside its normal southern and mostly coastal range.

Identification: Swarmers are about 1/2'' long including wings, which are approx 3/8" long. The head and pronotum of the swarmer is an orange brown and its abdomen is dark brown - see picture on left.

Key identifier: The front wing has 3 dark, heavily hardened veins in the front portion.

When the colony is about four years old it will, when the time is right, emit hundreds of reproductive swarmers from the nest. It is amazing how all the mature Wester drywood termite colony nests across an entire region, will swarm several times a year, but all at the same time. This is essential to produce new nests, to continue their 250 million year evolution.

Swarming typically takes place about mid-day on sunny, warm (80°F) days, with the peak of the swarm occurring shortly after a sudden rise in temperature. The swarming season usually occurs during September and October. Swarmers usually number in the dozens, occasionally the hundreds. Night swarmers are attracted to lights.

Identification of Soldiers - the forehead of which slopes down gradually from top of head. The head is flattened to slightly rounded in side view. The head is orange to reddish brown with the eye spot whitish - see picture on the left.

Soldiers have mandibles with unequal number of teeth on each member of pair, and antenna with the third segment greatly enlarged and club-like - as indicated by the red arrow in the picture to the left.

The soldiers are the defenders against intruders so if you open up timbers containing a drywood infestation it is the soldiers that first rush out to guard and defend the other colony members.

Although the colony development is slow, severe structural damage may still be caused by the presence of multiple-colonies. Their gallery and tunnel walls are velvety smooth, and no soil is present, unlike subterranean termites.

Another key identifier is that there is no workers present in Western drywood termite infestations; it is the nymphs perform all tasks typically done by workers.

Identification of Timber Damage: Drywood termites eat across the wood grain and create chambers, or galleries connected by tunnels.

Identification: Faecal pellets are found throughout their tunnels. Generally, there are faeal pellets present. They are hard, less than 1/32'' long, elongate-oval with rounded ends. One of the unusual distinctive signs of their faecal pellets is that they have 6 concave sides.

Control of Western drywood termites - firstly, obtain a professional termite inspection to determine the extent of an infestation and locations of other possible drywood termite colonies. The results of the inspection will dictate the best treatment options as no single control method is best for all situations.

Where the infestation is severe and extensive - the entire building may need to be fumigated wtth sulfuryl fluoride (Vikane.). Fumigation is a highly technical procedure which involves surrounding the structure with a gas-tight tarpaulin, releasing the gas inside the seal, and aerating the fumigant after a set exposure time. Before fumigation, the homeowner must remove all plants and animals from the house, remove or place food items inside special protective bags, and insure that there is sufficient tarp clearance between sensitive landscaping and exterior walls.

Where the infestation is only localized - it may sufficient to effect local spot treatments of the termite colony. An insecticide is injected into small holes drilled in the timber and into termite galleries. This is the simplest and most direct method of treatment. The amount of drilling required and the effectiveness of this treatment depends on the termite control products used and the nature of the infestation.

Links to other websites: Clemson University - Drywood Termites - TAMU University - Termite Control Pesticides - University of Arizona