Extension Educator, Horticulture
Earwigs prove to be more than a nuisance. Their name alone strikes fear. One can only imagine how they got their name. If the number of calls into my office are any indication, this is the year of the earwig. Wet weather has promoted large populations of the insect. Earwigs are usually not a major pest, but like cockroaches, just one found in the house is considered a major problem by many people. With high populations we can also see considerable damage to plants.
University of Illinois entomologist Raymond Cloyd shared some information on earwig identification and control in the recent issue of the U of I Extension Home,Yard and Garden Pest newsletter. Cloyd states the major earwig species is the European earwig. Adults are slender, reddish-brown, and approximately 3/4 inch long. The quick identification features are the large pincers that stick out from the hind end. 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 provide maternal care by nurturing and protecting the eggs and young, which is uncommon for insects. (Almost makes them lovable).
Earwigs are nocturnal hiding during the day and wreaking havoc 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. Earwigs are attracted to outdoor lighting. They enter homes to hide, but they don't breed. When inside homes, they may be mistaken for cockroaches, as they tend to resemble each other when it is dark and you are screaming.
Earwigs are not all bad. They are predators and eat aphids, mites, and insect eggs. However, their alter ego feeds on the flowers of plants, including marigolds, petunias, dahlias, and hostas. Earwigs eat small holes in plant leaves and flowers at 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.
Cloyd states 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 house foundation. Avoid overwatering plants and don't use thick organic mulch. Although not as healthy for plants, 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 earwigs are most likely to hide during the daytime. Check traps in the morning, and shake the insects into a pail of soapy water. A client called in with a suggestion for a trap made out of a cardboard paper towel roll smeared with peanut butter on the inside. She also mentioned a spray made of earwigs crushed in a blender. I don't think I'll join her for a milkshake soon.
If pesticides are an option, insecticides to control earwigs outdoors include carbaryl (Sevin). Do not apply Sevin directly onto flowers, because it is very toxic to bees and other beneficials. For best results, apply insecticides late in the day. Read and follow all label directions.
Earwigs that accidentally invade homes are primarily a nuisance since they don't cause damage or reproduce indoors. 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 indoors.
For information on other things that go bump in the night, check out the U of I Hort Corner Website.