Bug-busters

Farmers once fought off insects with sulfur, arsenic and mercury compounds. Today, the buzzing, crawling critters are held at bay with advanced insecticides meant to protect vegetation without harming anything, or anyone, else.

If only it were that simple.

Because there’s no free lunch in science, researchers are working continually on ways to improve the efficacy of insecticides while minimizing their impact on the environment — and its inhabitants.

An insecticide is any product or solution that prevents the proliferation of bugs, particularly when dealing with homes or vegetation. Advances in insecticides, which can kill, disrupt or limit bug populations, have helped agriculture explode in developed countries.

University of Maryland entomology professor Mike Raupp says not all bug-prevention methods are the same.

Some insecticides are administered via pressure pumps — workers shoot pesticides roughly 100 feet into the air.

“This is a technology that puts an awful lot of material into the environment. A good deal of it doesn’t go where you wish it to go,” Mr. Raupp says. “It can drift with a little bit of wind.”

If a neighborhood uses this method to, say, swat away mosquitoes, the side effects could have an adverse impact on another part of the ecosystem.

“You can knock out parasitic wasps that help control the pests on our trees,” he says.

That happened recently when local workers, trying to protect regional hemlock trees, unwittingly created a spike in the spider mite population through insecticides.

“Ultimately, the way I tell my landscapers is, ‘You’ve got to make a choice. Use this material and save a 300-year-old tree and suffer a mite outbreak,’” he says.

A modern approach to insecticide dispersion involves injecting chemicals directly into the soil or, in some cases, directly into the plants or trees.

The material “is taken up by the roots,” Mr. Raupp says. “It’s a major breakthrough.”

Frank Meek, an entomologist and technical director for Atlanta-based Orkin, says the biggest change in the pesticide field has come in the amount of active material used to defeat insects.

“Twenty years ago, we may have treated a house with [an insecticide with] 2, 5 or 10 percent active ingredient,” Mr. Meek says.

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