[Termite Control] Termite Treatments In The 21st Century

T ermite treatment has steadily changed over the last few years. Through the late 1980s and early ’90s, the emphasis was on the amount of termiticides applied, percentage of dilution, thoroughness of application and limitation of thin zones in the treated barrier. You could talk to any of the chemical manufacturing companies, researchers, regulators and consultants and their answer to most termite treatment problems was to increase dilution percentage (because the volume of termiticide applied ensures though application). Retreatments could be attributed to the amount of termiticide applied during the original treatment and follow-up applications.

But it appeared that the more repellent termiticides were applied, the more termites remained and continued to build exploratory tunnels (and on occasion, swarm). We now know that many of the termiticides being used were repellent to termites, so repellent in fact that the termites were actually prevented from crossing the treated barrier. This caused termites to live above the treated area or soil barrier and forced them to remain inside the structure until the conditions that are conducive to termites survival, i.e., moisture, harborage, food (cellulose) and favorable temperature, were no longer available in the infested area of the structure.

Although traditional wisdom at the time was that the termites would need to return to the soil for moisture, a termite actually only needs moisture of about 15 percent or higher to survive. In the early 1980s, the energy commission had begun to increase the amounts of insulation required in housing — for example, R-17 in outside walls and R-30 in attics. With this increase in insulation, the amount of condensation began to increase in houses. Termites could often live for long periods within a house without the need to return to the ground, just using the small amount of condensation that was created in the modern energy-efficient homes to meet their moisture requirements. Many times the control solution was not termiticide application but in fact opening up the infested area and allowing it to dry out (e.g., the wood moisture content at or below 15 percent).

NO MORE CHLORDANE. For 10 years or more prior to April 15, 1988, the day chlordane was taken off the market as a soil termiticide, it was the preferred termiticide of the pest control industry. Chlordane was a non-repellent termiticide even though most of us in the professional pest management industry did not know that. Termites that came in contact with chlordane were controlled, resulting not just in reducing risk for treated structures but also in reducing the general termite population that threatened the structures. With the reduction of the number of termites in a colony, and the reduction of colonies, structures in general were at less risk.

But non-repellents had not been used since chlordane was removed from the market on April 15, 1988, as a result of a voluntary agreement between Velsacol, EPA and environmental groups. Since these termiticides repelled termites rather than reducing their population, a build-up of termite populations around structures had increased the pressure for termites to infest houses. With this pressure the number of retreats continued to increase even though the termiticides were applied in accordance with labels and labeling instructions. The problem was not improper treatment, but increasing number of termites that resulted from the use of repellent termiticides. We now know that the best way to reduce the threat of termites is to control or reduce the number of termites that are available to infest a structure.

REPELLENT TERMITICIDES. With repellent termiticides, termites can be trapped inside the structure and if a small area is missed around the structure, the termites in their forgoing habits will continue to forage at the treated area until gaps or thin zones in the treatment can be located. These thin zones or gaps are created generally by objects like rocks, roots, clumps of compacted soil, roots of grass, insects tunneling through the soil, soil movement from planting plants, buried pipes, wires, etc.

From mid-1988 to 1996, the pest control industry used organophosphates or pyrethroids for subterranean termite control. Both of these could be repellent and did not substantially reduce the population of subterranean termites in some termite treatment procedures. Although Dursban at lower levels is also non-repellant, at label application rates, it appears to be repellent. Pyrethroids termiticides are repellent to termites. Termites sometimes continued to be active after being treated with the termiticides even when it was applied correctly, and completely following label recommendations.

BACK TO NON-REPELLENTS. In 1996 the termite industry was introduced to a non-repellent termiticide — Premise from Bayer Environmental Science. With the introduction of Premise in 1996, we returned to actually reducing the population of termites around a structure instead of just repelling the population away from the structure. This reduced the termite colony’s continuous foraging for a food supply, and retreatments begin to rapidly decline for the termite industry. Retreatments went from the 20 percent range to the now very common 5 percent or lower for jobs treated the year before. In the termite control business a retreatment rate of 5 percent or less is good since construction types and conditions conducive to infestations are often outside the control of the termite treatment professional.

With the introduction of non-repellent termiticides in 1996 and the introduction of Termidor, another non-repellent termiticide, in 2000, the game has changed in termite control. Retreatments of structures continue to decline to below the 5 percent range. Understanding the nature of termite control and the differences in construction, construction conditions, and conducive conditions that are present around construction that affect termite control a retreatment rate under 5 percent is a remarkable record in termite control when you consider termites are a native insect widespread in nature and are adaptable to most constructional conditions.

BAITS. In 1995 a different approach was introduced to the termite control industry —baits. Baits gradually reduce colony size in the area surrounding the house. Baits as a standalone treatment have proven satisfactory in control of termites; the problem is the amount of time required to achieve control — typically eight months or more. Combining bait technology with non-repellent termiticides can result in quicker control. Both baits and non-repellents reduce the population of termites that may be infesting structures, each contributing in its own way.

CONCLUSION. In the 21st century, those in the pest management industry have determined that the most effective control of subterranean termites is achieved by combining the tools of the termite control toolbox in a balanced procedure that may include correcting conducive conditions, baits and non-repellent technologies.

Since no one product results in complete control, every situation requires an independent control strategy termite control is an art and not a science. The keys to termite control are the usage of the available tools and the professional abilities of the pest management professional.

The author is technical director for Orkin Pest Control, Atlanta, Ga. He can be reached at phardy@pctonline.com.