The "Continuous Barrier" Is A Continuing Myth

The barrier was designed to prevent subterranean termites from entering the structure for food or leaving the structure for moisture in the soil. To ensure efficacy of termiticides, the Environmental Protection Agency needed proof that the toxicant in the soil would persist for at least five years.

This was provided in federal testing agencies in Mississippi and other sites where soil and termiticide solution were premixed in a cement mixer and placed under concrete slabs to simulate home construction.

Termiticide labels mandated by the EPA suggest mixing the soil with the termiticide solution in a shallow ditch along the foundation, or rodding down into the backfill but not below the footing. Pavement was to be drilled at intervals, depending on the type of soil, according to some labels.

A UNIFORM DISTRIBUTION? It was a Myth Conception of the regulators, the pest control industry and the public that the distribution of the solution by rodding would be uniform and that the barrier would be a series of contiguous columns of treated soil that would bar entry by termites. Testing in the field did indeed prove the residual value of the toxicant. But, for obvious reasons, no label calls for mixing all the soil to the footing with termiticide in a cement mixer.

It is not likely that the backfill around a foundation is uniform enough to permit an even distribution of termiticide solution. Building debris, brickbats, hunks of clay, trash and other items make it virtually impossible for every cubic inch to be properly treated. Some areas get too much and some too little or none at all. This is so even if the operator was meticulous about measuring and calibrating the application. As a result, the termite colony has plenty of time and foragers can find their “windows of opportunity.” When chlordane was used, it seemed to overcome these aberrations, possibly because of volatile isomers. This made chlordane a forgiving termiticide indeed.

According to Dr. Rudy Scheffrahn, a researcher at the University of Florida, the foraging range of the R. reticulitermes is about ¼ of an acre (l acre for the Formosan termite).

HIGH RISE INFESTATIONS. Another Myth Conception is the belief that once a soil treatment is completed, even under ideal conditions, the termite problem is solved. There have been a greater number of ‘high rise’ termite infestations than many termite controllers are aware of. Dr. Scheffrahn, among others, has agreed with me that above ground infestations are not uncommon. He suggests that if termites are found above the 2nd floor, it is unlikely that soil poisoning will affect them.

Dr. Harry Moore, a consultant from Raleigh, N.C., in an article in the February 1990 issue of Pest Control Technology, (“The ABCs of H2O in Termite Control”) lists several ways that water enters buildings. Among them, he states that “the porosity of masonry can carry water up 8 inches to structural wood.” There are other sources of water that can sustain a population of subterranean termites without contact with the soil. Many flat roofs are now covered with a membrane of a rubber-like material that outlasts conventional roof coverings. We have this on the condo that I live in. We thought our roof worries were over. But every time an air conditioning repairman solders a joint, a drop of solder opens a hole.

Many years ago, I described a serious termite infestation in a roof of a four-story food factory building. Built in the ’50s, shortages prevented extending to the 5th floor. One-inch steel rods intended to anchor supporting columns were covered with a wood box protected with roof paper. Termite swarmers from nearby buildings may have been swept up in the “Vertical Gulfstream” described in my Myth Conception column from the February 1994 issue of Pest Control Technology. They apparently had found a niche under the roof paper. Water that condensed nightly rusted the bars and seeped into the cellulose insulation covering the roof.

Other sites that can sustain subterranean termite colonies are shower stall pans, slow plumbing leaks, wood wetted due to clogged roof gutters, shrunken caulk around exterior openings, saturated mulch piled high enough to touch wood siding, etc. Vapor barriers are sometimes installed on the wrong side of an exterior wall. This allows condensed moisture to wet studs and plates.

FALSE GUARANTEES. It is, in my opinion, a universally accepted Myth Conception that a termite job can be guaranteed for five years, as has been the practice for decades. The termite colony that we thought was eradicated may have been only a satellite of a huge colony, a mega-organism capable of returning again and again. I believe termite control contracts should be written as they are for other pests: for monitoring (especially with a moisture meter), and spot treating with termiticides as they appear, supplanted with bait stations that are checked regularly, with all of this being renewed annually.

After all, what other discipline in the life sciences guarantees its work?

Harry Katz may be contacted at Berkshire E-3076, Deerfield Beach FL 33442, 954/427-9716.