Sep. 18, 1998 GAINESVILLE---You've got your security system on, burglar bars up and guard dog at the ready. Feel safe?
You shouldn't. The tiniest home invaders of all can still get in, say University of Florida researchers who are studying subterranean termites.
"Most homeowners have a false sense of security that they're protected from termites with the barrier treatments that have been popular in the last 10 years," said Tom Powell a graduate researcher at UF's Urban Entomology Laboratory. "But in the real world, there are often gaps in the treatment barrier that leave termites a path to your home."
With up to two out of three Florida homes built since 1988 experiencing termiticide failures, controlling the little home-breakers might seem a lost cause. But researchers hope to use new findings to thwart them, said Phil Koehler, an entomologist with UF's Institute of Food and Agricultural Sciences who is supervising Powell's research.
"Since 1988, termite repellents have been used widely in an attempt to create a barrier underneath and around homes. The thought was that a termiticide had to be repellent to protect a house," Koehler said. "The problem with this approach is that there are almost always gaps in the treatment. Termites who are repelled by a termiticide at one spot will turn around and keep foraging for access to your home and keep trying until they find a gap."
The problem with repellents is that they do exactly what they are designed to do -- repel termites. A better approach is to kill termites, said Koehler and Powell.
Powell has been researching termiticide failures in a unique test of termite behavior around barrier treatment gaps. In his findings, which follow, imagine that "home" is your own home.
In the laboratory, Powell filled eight, flat containers with soil and treated middle portions with various termiticides, both repellent and non-repellent. On one side of the treated soil he placed a wooden block to represent a home. On the other side of the treated soil, he introduced termites.
When he treated the soil with repellent termiticides to represent barrier treatments, the termites found the gaps and reached the "home" in an average of 30 days.
To replicate real-world conditions, in which a pipe could be laid after a treatment thereby creating a gap, he inserted objects in the gaps. In those experiments, the termites reached "home" in an average of just four days.
In experiments using non-repellents, however, there was 100 percent mortality of the termites in 15 days -- and they never reached the "home."
"A repellent is toxic to the termites if they contact it -- in fact, more toxic than non-repellents -- but they will never come into contact with it because they can detect it and avoid it," Powell said. "They don't detect a non-repellent, though, so even if they do find a gap, chances are that they have also tunneled into the treatment and contacted enough to kill them."
Non-repellents kill termites when they orally manipulate the treated soil during their foraging behavior. Currently, six of eight termiticides on the market are repellents, but Powell said he believes the market will shift toward non-repellents.
Termite treatment and damage costs $500 million a year in Florida alone. It became an issue in the last decade following a ban on chlordane in 1988, Koehler said.
Chlordane, a non-repellent, was the gold standard in termite protection because it did the job and had staying power. Too much staying power for the U.S. Environmental Protection Agency. With residual properties lasting 35 to 40 years, chlordane's asset became its downfall, and the EPA banned it because of concerns about excessive human exposure in some houses and in some types of construction.
Homes treated with chlordane in the 1980s have residual protection to rely on. But homes built since 1988 have had to rely on less effective termiticides. With as many as 118,000 new homes going up each year in Florida, that's three squares a day for a lot of termites.
"In houses built since 1988, there has been a very high incidence of termiticide failures. It's a very real problem," Koehler said. "We've been looking at a phenomenon, that when a house is built, up to two of three will have failures. I've seen 2-year-old houses with $20,000 in damage."
Koehler, who headed up a legislative pest control study committee in 1997, said new building codes are needed to protect homeowners. He suggests a St. Johns County code as a model because it eliminates food sources that attract termites and eliminates hidden access. It also requires down spouts to discharge rain water at least five feet from a building and provides a $50,000 warranty for the homeowner after all precautions are taken.
"Construction practices now allow termites to enter without being seen by the homeowner," Koehler said. "We need to prevent access from being built into a person's home. This is a problem that can be corrected."
Koehler said subterranean termites are the most destructive insect in Florida.
"Several termite colonies can feed on a house at one time," he said. "Some of these subterranean colonies are equivalent to a 50-pound animal eating up to one pound of wood each day."
Most homeowners don't even know what a termite looks like, Powell said, but with colonies averaging 250,000 termites each homeowners would be advised to become acquainted with their subterranean neighbors.
Homeowners who are relying on repellents can take some consolation in a requirement that the treatment last five years, Powell said.
"But," he said, "the best protection is a dead termite."
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