Extension Educator, Horticulture
Big leaves, little leaves; all riddled with holes. What could it be? No critter in sight. No critter to blame. Could it be slithering slimy slugs? But where were the slime trails? Where was the yuck? Then a quick stirring of the mulch and a scream full of earwigs race for refuge. UGH! Earwigs:The poster child for creepy crawly.
Earwigs are usually not a major plant pest, but our recent wet weather has spawned large populations of European earwig. Adults are slender reddish brown and approximately 3/4 inch long. The quick identification features are the large pincers on their hind end. The pincers are used for protection against predators and 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 (not in your ears in case you were wondering). The females provide uncommon maternal care by nurturing and protecting the eggs and young. (Almost makes them lovable).
Earwigs hide during the day and wreak havoc on plants at night. They prefer moist areas. 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 not all bad. They usually eat decaying plants. As predators they eat aphids, mites, and insect eggs. However, they are equal opportunity eaters as they feed on the flowers and leaves of ornamental and vegetable plants including bean, potato, beet, cabbage, pea, zinnia, marigold, petunia, dahlia, hosta and even ripe apples and peaches. Damaged leaves and petals have a ragged appearance with irregularly shaped holes throughout the leaf. Seedlings and flowering plants can be severely damaged or killed by large earwig populations.
Earwig management includes sanitation, cultural practice modification, trapping, or insecticides. Remove outdoor harborage such as firewood, plant debris, weeds, and organic mulches from around the house foundation. Avoid overwatering plants and thick layers of 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, cardboard paper towel roll, small board or an 8-10 inch section of garden hose can be used to trap earwigs. Place traps in areas showing damage. In the morning shake the traps over a pail of soapy water.
If needed, insecticides to manage earwigs include cyfluthrin, permethrin (Eight) and carbaryl (Sevin). Read and follow all label directions. To help protect beneficials and bees, do not spray directly on flowers.
Earwigs that accidentally invade homes are primarily a nuisance and a vacuum will take care of them. They don't cause damage or reproduce indoors. To prevent earwigs from entering homes, caulk cracks and crevices, weather strip doors and apply outdoor foundation insecticides. Check cut flowers, baskets or anything that has been outdoors for hitchhikers. Chemical treatments are generally not necessary indoors.