Great Plains Gardening

By Edith Koeller

August 20, 2004

Have you seen an earwig today? Or do you know what they are?

"The common earwigs found in Colorado are an introduced insect that arrived in the state during the 1950’s. The European earwig is an insect migrant from Europe that was established in the eastern Untied States around 1907 and has rapidly spread across the Untied States."

"The European earwig is about 5/8 inch long and brown with a reddish head. Young earwigs are similar in appearance to adults but smaller. A distinct feature is the pair of prominent forceps (cerci) at the rear of the body. Those of the male are more strongly curved than those of the female. This is the only earwig found throughout most of Colorado. In the extreme southern areas of the state, a second species may be seen: the ring-legged earwig, readily identified by a band on the forelegs."

"Ear wigs are a common nuisance both indoors and out. During the day; they hide in almost any dark, confined space, particularly if it also is rather moist. Typical indoor hiding places are under rugs or potted plants, in stacks of newspapers, and similar locations. Outdoors, they commonly are found under rocks or stacked wood, in ear tips of sweet corn, and under various kinds of debris; Peak problems with earwigs in Colorado tend to occur from mid-July through mid-September."

"Earwigs are active at night and feed on a wide variety of materials. They occasionally cause injury to leafy plants such as lettuce and some flower blossoms. They often are associated with injuries caused by other insects. For example, leaves curled by aphids and holes in fruit are favorites hiding places for earwigs."

"Earwigs mainly are a nuisance pest. Their reputation is made worse by the widespread fear that many people have regarding these insects. Several tales exist concerning alleged damage of earwigs; how they like to crawl into ears or how the forceps cause a painful pinch. These stories have little basis in fact, although earwigs have been known to cause a mildly painful bite when sat upon or handled. Overall, earwigs may actually be considered beneficial—they feed on many plant pests, such as aphids, mites and insect eggs. Earwigs have been used for biological control of some plant pests. However, there are situations where control of earwigs is desired."

"Outdoor control of earwigs is best achieved by combining several measures. Reduce movement into homes by clearing the area next to the house of debris or other materials that provide shelter. This is particularly effective if a relatively dry barrier zone, disagreeable to earwigs, is established around the home. Trapping and destroying the insects can provide limited control of earwigs in a garden. An effective trap is a moistened, rolled-up newspaper placed in the garden overnight and then disposed of or crushed in the morning."

"Insecticides may be used in a variety of ways depending on the situation. Barrier treatments of insecticides sprayed along the exterior foundation walls and as a 1 to 3 foot swath along adjacent soil can prevent movement of earwigs into the home. Trunk banding may be considered if there are problems with earwigs damaging fruit trees. However, most earwig feeding is on insects such as aphids, which cause leaf curl and produce honeydew. Use of insecticides applied directly to crops is not recommended and should be done strictly in accordance with label directions."

"Use indoor controls only in addition to exterior treatment. Otherwise, results will be unsatisfactory. Exterior treatment includes sealing all cracks in the foundation and around windows and other openings to reduce earwig movement into homes. Individual earwigs found indoors may be vacuumed or spot treated with spray-and-wash indoor cleaners that kill by contact. Such insecticides as Dursban, Diazinon and Baygon, which are formulated for interior application, also may be used. Apply them only to areas in the home used for earwig shelter and not as a general household spray. Closely follow label instructions for these interior uses.

This information comes from CSU Fact sheet #5.533, available at the Extension Office.

Until next time…