Recent wet weather in parts of Illinois has resulted in a noticeable increase in earwig populations. Earwigs are not a major pest; however, they do feed on flowers and can be a nuisance inside homes. Unusually wet springs and summers tend to intensify earwig infestations.
The major earwig species is the European earwig, Forficula auricularia. Adults are reddish brown and approximately 3/4 inch long. They resemble rove beetles, being slender with short wing covers. Both the males and females have large pincers (cerci) that stick out from the back of the abdomen. The pincers are used in defense for protection against predators or to capture prey. Earwigs hibernate in the soil as adults during the winter. In spring, adult females lay 25 to 30 eggs in the soil. The females nurture and protect the eggs and young (maternal care), which is uncommon for insects. Earwigs are nocturnal, which means they hide during the daytime and are active at night. They tend to prefer moist environments. During the daytime, they usually inhabit dark confined or shaded areas, such as underneath plants, debris, stones, organic mulch, tree bark, and flower pots. They are less likely to be found in exposed sunny areas. Earwigs will enter homes to hide, but they donít breed. When inside homes, earwigs may be mistaken for cockroaches, as they tend to resemble each other when it is dark. Earwigs are known to be attracted to outdoor lighting.
Earwigs are predators and eat aphids, mites, and insect eggs. However, they also feed on the flowers of plants, including marigolds, petunias, dahlias, and hostas. Earwigs eat small holes in plant leaves and flowers during the night. Leaves and petals have a ragged appearance with irregularly shaped holes. Seedlings and flowering plants can be severely damaged or killed by large earwig populations.
Earwig management includes sanitation, modification of cultural practices, trapping, or the use of pest-control materials. Remove outdoor harborage such as firewood, plant debris, weeds, and organic mulches from around the foundation of a house or building. Avoid overwatering plants and donít use a thick organic mulch. Inorganic mulches such as lava rock or stone are less attractive to earwigs. A moistened rolled-up newspaper, inverted old tuna fish can, or an 8- to 10-inch section of garden hose can be used to trap earwigs. Place traps in shaded areas where ear-wigs are most likely to hide during the daytime. Check traps in the morning, and shake the insects into a pail of soapy water.
Pest-control materials that may be used for controlling earwigs outdoors include granular or wettable powder formulations of carbaryl (Sevin) or chlorpyrifos (Dursban). Do not apply these insecticides directly onto flowers, especially Sevin because it is toxic to bees. For best results, apply insecticides late in the day. Earwigs that accidentally invade homes are primarily a nuisance because they donít cause damage or reproduce inside the home. To prevent earwigs from entering homes, caulk cracks and crevices and weather strip doors. Earwigs that are found inside the home can be vacuumed. Chemical treatments are generally not necessary.