Are Earwigs Damaging to My Garden Plants?
USU Extension Entomologist
Earwigs are common garden pests in northern Utah. They chew into buds, leaves, flowers and fruits of many plants, including tree and cane fruits, vegetables and ornamentals.
Their typical damage is small, ragged holes chewed in plant tissue. Earwigs will chew off corn silks and hide inside ripe apricots and peaches next to the pit. However, they are omnivorous and will also eat decaying debris and pollen and are opportunistic predators of other insects. Earwigs are active at night and seek protection during the daytime.
Their eating habits and behaviors make them both a pest and a beneficial insect. The best management is a balance of protecting plants from injury while reaping the benefits from the biological control and organic matter decomposition they provide. Their prey includes aphids, caterpillars and other small garden insect pests.
The European earwig was introduced into North America from Europe. The common name "earwig" comes from a myth that it would climb into the ears of humans and chew into the brain, but this is false. The first record of its presence in Utah was in the 1930s.
Consider this information in developing a management plan for earwigs.
An inexpensive and easy trap can be made from rolling up 4-inch strips of one-sided corrugated cardboard with the ridges facing inward and tying it onto a tree trunk or plant stem. Earwigs will seek shelter in the traps during the day. The cardboard rolls can be opened up, the earwigs dumped into a container of soapy water, then the cardboard can be tied again to the trunk. These traps become more attractive after repeated use since earwigs leave odors behind that attract others. Adding food bait, such as wheat bran or germ, can increase earwig catch.
A trap that is best suited for flower, herb and vegetable beds can be made from a plastic yogurt or sour cream container. Punch five or six 1Å½4-inch diameter holes around the top of the container and add 1Å½2 to 1 inch of vegetable oil with smelly bait, such as meat juice (liquid from canned tuna works well), bacon grease or soy sauce. Place the lid on the container to keep out rainfall and irrigation water as well as animals that may want to eat the bait. Bury the container into the soil so the holes are 1 to 2 inches above the surface. Check the traps several times each week, dispose of dead earwigs and replenish the trap with fresh bait.
Earwigs will climb trees and plants to feed on fruit. Prevent this by placing a band of sticky adhesive, such as Tangletrapâ¢, around the trunk or stem. Brush or spray the adhesive on a surface, such as duct tape, to protect tree bark.
Earwigs can also be nuisance pests when they enter buildings to seek shelter. Seal cracks and crevices, install under-door sweeps and ensure that screens are tightly sealed to help prevent their entrance. Remove vegetation and debris (including mulches) next to buildings in areas where earwigs may enter such as near doorways and basement window wells. Apply insecticides as a barrier treatment around foundations.
Use traps and exclusion barriers first before resorting to insecticides. To conserve beneficial insects, only apply insecticides when deemed necessary. Insecticides that are effective for earwigs and registered for use around the home include spinosad, carbaryl, diatomaceous earth, azadirachtin, malathion, bifenthrin, cyfluthrin, cypermethrin, deltamethrin, lambda-cyhalothrin, permethrin, and pyrethrin. Always read the insecticide label for registered uses, application and safety information.
For more information about earwigs, see the USU Extension fact sheet at
http://extension.usu.edu/files/publications/factsheet/earwig-orn.pdf or watch a video on how to make homemade earwig traps at http://utahpests.usu.edu/htm/video-fact-sheets.
Direct column topics to: Julene Reese, Utah State University Extension writer, Logan, Utah, 84322-4900; 435-797-0810; firstname.lastname@example.org.