JoAnne Skelly: Earwigs are creepy, but are they bad?

Mary, a reader from Gardnerville, said, “I have a terrible time with earwigs, my most dreaded pest; and the sight of them makes me cringe.” Yes, earwigs do look alarming with pincers at their hind end. They even bother seasoned gardeners who normally have an attitude of “live and let live.”

Earwigs, believe it or not, are primarily beneficial. They mainly eat and break down organic matter, which includes dying and dead plants or ripened fruits. They also eat petals, pollen and seedlings. Typical earwig damage on most plants is small holes in the margins of leaves. Whole seedlings may disappear. They chew shallow gouges or holes in fruit. To their credit, they sometimes eat other insects, mites, nematodes, algae and fungi. Earwigs are often blamed for damage more likely caused by slugs, cutworms and other garden pests that also may hide in damp debris. Gardeners often assume damage to fruit and vegetables is caused by earwigs, when the earwigs came after the initial attackers. However, their eating of the silks on corn plants can cause poor kernel development.

One way to deter earwigs from nibbling on plants is to circle them with organic matter, such as compost or chipped bark, to provide a complex soil surface with many organisms on which they can feed instead. If your yard is already well mulched, and you suspect earwigs are chewing on your seedlings, raise the seedlings indoors and transplant them outside when they are large enough to withstand damage.

Earwigs are easy to trap. Place small cans with a half inch of vegetable oil in them around the affected plants. Bamboo tubes, dampened rolled up newspapers, damp rags or pieces of hose also make good traps because earwigs like dark moist places. A clay or plastic pot filled with damp moss and placed upside down with a small gap at the bottom provides an inviting earwig abode. Place traps near plants just before dusk. Check traps the following morning and shake the trapped insects into a bucket of soapy water to drown them. Reset the traps daily.

Keep earwigs out of mature trees by encircling the bark with a six-inch band of a sticky barrier. There are products sold for this. Diatomaceous earth also works as a barrier. Remove boards, rubbish and plant debris in areas you want to protect to reduce hiding places. Raise pots and plant containers on stands or pot feet to deter earwigs from collecting in them.

JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at skellyj@unce.unr.edu.