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Drywood Termites
The western drywood termite, Incisitermes minor,
is Texas’ second most important termite pest after the western subterranean termite. It is a native insect that has
been here millions of years, mostly attacking trees along river washes and arroyos. In Texas drywood termites are most prevalent
in southern Texas and can be found infesting wood along the coast.
Because of the difficulty in detecting drywood termites and determining the extent of the damage done, do-it-yourself treatments are not recommended. Over-the-counter products with drywood termites on the label for do-it-yourself enthusiasts do not exist. Except for wood removal, homeowners should seek help from pest control professionals. Detection Drywood termites are secretive insects and are difficult to detect. They live deep inside wood and are seldom seen except during periods when they swarm or when repair work is being done on infested homes. Colonies are small – usually fewer than 1,000 individuals – can be widely dispersed, and takeyears to mature. While a homeowner may initially detect the presence of termites when they swarm or if fecal pellets are discovered, inspecting for drywood termites and determining the extent of an infestation require experience. During a visual inspection for drywood termites, inspectors look for feeding damage, shed wings, termite fecal pellets, and kickout holes, which are small holes the size of BB shot through which termites push fecal pellets out of the wood. Fecal pellets are hexagonal in shape and are diagnostic for drywood termites. However, whether the infestation is currently active or what the extent of the infestation is cannot be determined from pellets alone. Cleaning up the fecal pellets around a kickout hole and checking a few days later to see if new pellets have appeared can help to determine if an infestation is active. Keep in mind that building vibrations or movements may cause some pellets to appear. If an active infestation of drywood termites is found in your structure, you should have it treated. Eliminating Existing Infestations All drywood termite control methods can be categorized as either whole-structure or localized. A whole-structure treatment is defined as the simultaneous treatment of all infestations, accessible and inaccessible, in a structure. A localized or spot treatment is more restrictive, often applied to a single board or small group of boards. Whole-structure treatments have an advantage over spot treatments in that they can eliminate all infestations, even hidden ones. With the uncertainty of current detection methods, particularly when drywall or other wall coverings conceal infestations, there is always some doubt as to the extent of drywood termite colony boundaries within homes. Consequently, one can never be sure that all infestations have been treated when applying spot treatments. Whole-Structure Treatment Fumigants (sulfuryl fluoride) treat all infestations simultaneously and have high levels of efficacy applied correctly. Sulfuryl fluoride kills drywood termites in about three days. A monitored fumigation, which involves installing gas monitoring lines inside the structure being treated, has the highest rate of treatment success. Unmonitored fumigation may not have enough gas concentration to kill infestations and failures may occur. Fumigation’s advantage of localized treatment is that it may eliminate infestations that are hidden from view. Major issues to consider with the use of fumigants include the difficulty of installing tarpaulins, the difficulty in determining the proper dosage, the need to protectively bag food items, and the lack of residual control. Residual control means long-term protection (several years or more) from drywood termite attack. (Generally, only chemicals added to or onto wood provide residual control.) It will also be necessary to vacate the structure for two to three days while it is being treated and then ventilated. Roofs may be damaged by having tarpaulins dragged across them. Localized or Spot Treatments There are many localized or spot treatment methods available that include both chemical and nonchemical options. Spot treatments should only be applied by licensed professionals. Home use products are not effective. Depending on the chemical used for spot treatments, laboratory studies have shown a variation of 13% to 100% in the effectiveness in controlling drywood termites. |