It’s Earwig time again

It’s Earwig time again

By By Dr. Robert A. Hedeen

By Robert A. Hedeen


From early summer until late fall, we in northern Illinois are apt to encounter an odd and dangerous-looking insect invader of our homes. In all probability, this pest is a European earwig and is easily recognized by the presence of a pair of intimidating forceps-like, pincer appendages projecting from the rear of its body.

Earwigs belong to the Dermaptera (skin-wings) order of insects. There are some 20 species of earwigs to be found in America north of Mexico with the so-called European earwig being the most common and widely distributed. Most earwigs have two pairs of wings, the forward pair being leathery and serving as coverings for the functional rear pair. Earwigs are usually dark brown in color and may measure an inch or more from the head to the tip of the forceps. They have chewing type mouthparts, and the type of development is similar to that of grasshoppers and roaches, to which they are related.

The earwig gets its common name from the mistaken belief the pesky little critter has the nasty habit of routinely crawling into human ears and inflicting damage to the inner ear and even the brain. This notion, which originated in Europe, has persisted for close to a millennium. An earwig may, on a very rare occasion, find its way into a human ear, but no more often than any other insect. The reason this legend and folk belief has lasted so long is due to the insect’s suggestive name and the fact they do prefer dark, moist places—attics, basements, and such—but not ears!

The male earwig has forceps or pincers that vary from about half as long or longer than the abdomen with a set of teeth near the base. The female earwig’s forceps are less than half the length of the abdomen and lack the prominent basal teeth. In addition, there is an outward bulge in each of the male’s pincers, whereas the pincers of the female are more are less parallel to each other. If, for some unknown reason, one handles a large earwig, the forceps-like pincers may give a painful nip, but the skin will not be broken. Entomologists were baffled for years trying to determine the primary use of the pincers. Now it has been decided they are used for capturing and holding prey.

Earwigs feed on almost anything: other insects, plants, ripe fruit, and decaying garbage. Plants for which they have a special liking include lettuce, strawberry, zinnias, celery, various beans, and tender grass shoots and roots. Large earwig populations, on occasion, have been noted to cause considerable damage to corn by feeding on the silks.

Earwigs are nocturnal, hiding during the day and roaming far and wide at night in search of food and water. Around our homes they hide in garden plants, in shrubbery, along fence lines, in woodpiles, in the mulch in our flower beds, under sidewalks and stones, and behind loose boards on buildings.

They enter homes as they can somehow manage to find ports of entry like doors and windows and by climbing up the foundation of a dwelling. Large numbers of earwigs can build up quickly around foundations and frequently present a major problem in new subdivisions. In general, these insects live in the same habitat as sow bugs, centipedes, millipedes, and harvestmen (daddy longlegs).

Control of earwigs should begin outside of the home by removing mulch, leaf litter, and pine straw from around the foundation. Then, a general-purpose insecticide, in either a dust or spray, should be applied around the foundation and other possible entry sites. The label on many general-purpose insecticide formulations will list earwigs as one of the pests the product will control. If one does not choose to use an organic insecticide inside the home, a dry or wet mixture of equal parts boric acid and sugar placed in dark, damp locations will frequently alleviate the problem. A dry mixture of 10 percent plaster of Paris and 90 percent sugar has also been recommended, but considerable time is required for this concoction to produce results.

Earwigs can definitely become a nuisance around the home, especially when new colonies build to high population levels. The insect is much disliked by the average person because of the old wives’ tale it may set up housekeeping in your ear, its repulsive appearance, and the foul-smelling odor they emit. This characteristic odor may be a mechanism of defense or a pheromone used to bring the sexes together for mating.

Earwigs, like all other species, fill a niche in the overall ecology of an environment and are beneficial to man by devouring aphids in the garden and obnoxious cockroaches in the house. But if you find an earwig in your house, there is absolutely no need to purchase a pair of earplugs to be worn while sleeping.

Dr. Robert Hedeen is a former resident of eastern Maryland, with degrees in zoology and botany. He is a former professor of biological science. He has had 30 scientific papers published, has written numerous magazine articles, and is the author of two books on marine biology of Maryland.

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