Many homes across the country are vulnerable to subterranean, drywood and dampwood termites infestation. In northern climates, however, drywood termites cannot live outdoors so they have not established themselves in those areas. There have been isolated cases of drywood termite infestation in homes as far north as Ohio and New York, but those are very rare.
Drywood termites build their nest in perfectly good wood that is not decayed and not in contact with the ground, hence the name ‘drywood’. In many cases, they establish a colony in the wood-framing members of the attic. Just like subterranean termites, reproductive drywood termites swarm from the nest periodically, in an attempt to establish a new colony. Drywood termite swarmers often do not fly more than a few feet before settling down, but if aided by air currents they can flow more than a mile. In homes, drywood termites can be found in rafters, studs, joists, sheathing, window frames, door frames, floorboards and exterior trim.
Once a colony is established, it feeds on the wood around the nest. Drywood termites are general feeders and consume spring- and summer-grown wood, so the galleries formed will cut across the grain. The cavities contain tiny, seed-like, generally straw-colored pellets of partially digested wood. Sometimes, some of the pellets are pushed through openings in the wood surface. Pellets are often the first sign of infestation, but if there is not much accumulation they can be easily overlooked.
According to estimations, the maximum population of a fully-established drywood termite colony is about 3,000 – considerably less than the typical number of subterranean termites in an established colony, which is estimated to be between 60,000 and 250,000. Consequently, it takes longer for serious damage to occur with drywood termites than with subterranean ones.
How to Manage Drywood Termites Infestation – Treatment Methods
Drywood termites do not nest in the ground, so they must be chemically treated at the source of infestation. Usually, this is done by injecting insecticide into the drywood termite galleries, a procedure that should be performed by professionals. To reach the galleries, holes are drilled in the infested wood members. The insecticide will be either a liquid or a dust. When the wood is dry, dusting can be effective as far as 15 feet from the point of application. When the wood is wet, however, dusting is not as effective because the dust tends to cake in the moist galleries. If drywood infestation is found on a fence or pole on the property, those members should be chemically treated since termites represent a potential source of infestation for the house.
In cases of severe infestation, treatment usually involves fumigation. The entire house, including the roof, is wrapped with a plastic covering, and a poisonous fumigant is introduced after all the openings are sealed. The houses should remain under fumigation for at least 48 hours. The insecticide is poisonous to humans, so fumigation should be performed only by experienced fumigators.
Drywood Termite Control – Inspection and Prevention
Because drywood termites do not leave their nest in search for food, there are no obvious signs of infestation such as shelter tubes. Still, they can be detected by their pellets, which tend to accumulate in a small pile after termites push it from the wood or fall through a crack in the infested wood. Also, an infestation in the house can also be detected by the presence of drywood termites swarmers, of you happen to be in the room when the swarming occurs.
Drywood termites can attack wood located anywhere in the house, from the crawl space to the attic, so a termite and other wood destroying insects inspection should include checking all exposed wood for signs of infestation. The wood should be gently probed, so as not to break the surface. Since infested wood has hollow sections, if heavily probed it can break open, spilling the seed-like pellets. Moreover, drywood termites often consume wood up to the paint itself, forming what seems to be paint blister. This blister can break at the slightest pressure. To ensure the integrity of the wood surface, the wood members must be properly maintained, inspected from time to time and treated whenever necessary.