Detecting the extent of damage done by drywood termites is difficult, so experts do not recommend over-the-counter remedies for drywood termite treatment. These termites live deep inside the wood and show wide dispersal. Usually, the extent of feeding damage, the number of shed wings and fecal pellets, and the number of kick-out holes gives an idea of the severity of infestation. The drywood termite’s fecal pellets are hexagonal in shape, and the kick-out holes are usually the size of a BB shot. The termites use this hole to push their pellets out of the wood.
Drywood termite control methods are categorized into two types: whole-structure, and localized or spot treatments. The whole-structure treatment deals in treating the whole infected structure—both visible and invisible parts—and is much more effective. The localized treatment, as the name suggests, deals with a particular infested area; hence, it is more restrictive.
If correctly applied simultaneously, it is possible to achieve high levels of efficacy with fumigants. In about three hours, the termites get killed. A monitored fumigation, which needs gas monitoring lines to be installed inside the infected structure, has the highest success rate. Non-monitored fumigation does not have the same rate of success as there may not be enough concentration of gas to kill the infestations. This process is also known as termite tenting and it comes with some distinct disadvantages. Whole-structure treatments should be performed by professionals.
- The difficulty of installing tarpaulins
- Determining the proper dosage of fumigants
- Protecting food items
- Lack of residual control (long-term protection from termite attacks)
- Vacating the building for 3 to 4 days during treatment and, later on, during ventilation
- The possibility of roofs getting damaged due to the use of tarpaulins
In the heat method, the affected structure is heated to a minimum of 120°F, and the heat is maintained for at least 33 minutes. With this method, whole structures can be treated without the use of chemicals. The structure needs to be evacuated only for a few hours, as opposed to the few days required with other fumigants. Huge buildings, such as condominiums and apartments, can be treated in stages, instead of at one go. The heat method is used for spot treatment as well.
Sometimes a difficulty may crop up in raising the internal core temperature of the large infested structural beams
Damage to heat-sensitive items, such as plastics, electric outlets, and cables
No residual control
There are chemical as well as non-chemical treatments available, such as with aerosol, liquid, and dust insecticides. For the liquid and dust methods to be practical, the termites should touch or ingest the insecticides. Spot treatments should be applied only by licensed applicators. Some of these treatments have shown 13% to 100% effectiveness in eliminating termites. Treatment with liquid nitrogen is a successful spot treatment method. It causes a sudden drop in temperatures, which kills the termites.
Liquid nitrogen has no residual activity when used alone.
Small amounts of damage occur as holes have to be drilled for chemical insertions.
Microwave devices used for spot treatment kill the termites inside the wood itself. They leave no chemical residue.
Accuracy in detection is critical to the success of such devices.
They may damage the surface or interior of the wood boards.