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Perimeter Invaders and their Control


When exterminators use the terms "perimeter invaders" or "occasional invaders," they're referring to a wide variety of creatures who commonly live outside, but who occasionally make their way into buildings. There are literally hundreds of such creatures. We're just mentioning a few of them here.

Earwig. Photo courtesy of Humboldt State UniversityEarwigs average about 5/8" in length when full-grown. Despite the scary-looking pincers at the rear of their abdomens, they are harmless. (They don't really crawl into people's ears and make them insane, as an old English wives' tale taught.)

Earwigs tend to live in moist areas that are protected from predators, such as under rocks or in mulch. They are scavengers for the most part, feeding mainly on decaying animal and plant matter.

Sowbug. Photo courtesy of the University of IdahoSowbugs and pillbugs are not really bugs. They are crustaceans, and are more closely related to lobsters than to insects.

About 1/2" in length when full-grown, sowbugs and pillbugs resemble tiny armadillos. Children often refer to pillbugs as "roly-poly bugs" because they roll up into tight little balls when they are touched.

Both species are semi-aquatic and require very high moisture levels to survive. When they do wander into homes, typically die of dehydration within a day or so.

Click BeetleBeetles are members of Coleoptera, the most populous order of animals on earth. In fact, one out of every five animals in the world is a beetle.

Only a relatively few beetle species are pests, such as those that destroy crops or infest stored food. The rest are, at worst, a minor nuisance. The beetle at the right, commonly called a "click beetle," sometimes enters homes and is often mistaken for a cockroach by frantic homeowners. But it is harmless.

Do-It-Yourself Control of Perimeter Invaders

Generally speaking, the presence of perimeter invaders indicates that there is a moisture problem or structural flaw (like cracks in the foundation or gaps between the foundation and the sill plate) around the perimeter of a house. Most problems with perimeter invaders can be treated non-chemically by sealing openings in the buildings perimeter walls, rectifying moisture problems, cleaning up decaying organic matter, and substituting inorganic products like gravel or crushed stone for organic ones like wood chips or similar landscaping materials in the few feet of space around the building.

Occasionally, however, perimeter invaders become a serious enough problem that chemical treatment is warranted.

Even when pesticides are required, you should use the above non-chemical methods first. Pesticides should be considered supplemental to non-chemical measures, rather than the primary treatment.

Perimeter invaders can be controlled with any of a variety of properly labeled liquid or granular insecticides applied around the building's perimeter. Usually, granular products sprinkled around the home in accordance with the label instructions are the simplest and most effective method for homeowners.

Some perimeter invaders, particularly ants, crickets, and silverfish, respond well to granular insecticide baits. Baits that use borates as their active ingredient are considered among the least hazardous of pesticides, although bait products in general are considered relatively non-hazardous and easy to use.

Another option is to use a liquid insecticide applied around the home either with a handheld pump-type or compressed-air sprayer, or one that attaches to the end of a garden hose and siphons and automatically mixes the insecticide from an attached container.

Whatever method you use, always read and follow the label instructions, making sure that the pesticide is registered for the specific pest, the area you wish to apply the insecticide to, and the method of application you are using. Always avoid the temptation to apply more insecticide than is specified on the label. Excessive application will not improve the products effectiveness, but it will increase the hazards to humans, wildlife, domestic animals, and ornamental plants.