How to Control Earwigs

A living contradiction, earwigs are both a beneficial insect and a garden pest.

April 19, 2012

Found throughout North America, these omnivores eat decaying organic matter such as mulch or compost. They are beneficial in that they eat aphids, mites, and nematodes. However, they also eat ornamental and vegetable plants, particularly dahlias, zinnias, butterfly bush, hollyhocks, lettuce, strawberries, potatoes, roses, and seedling beans and beets, as well as the silk of sweet corn. Usually the damage is minor, unless their populations are high. Earwigs hide in cool, moist places during the day and feed at night. They are unusual among insects in that the female fusses over her eggs and nymphs, and uses her pincers to protect them. Adults overwinter in the soil.

Earwig damage mimics damage from caterpillars and slugs; be sure you've identified the real culprits by looking for feeding earwigs on your plants after dark. Make traps from rolled-up newspapers or cardboard filled with straw and taped shut at one end. Place them near plants and dump the contents into a bucket of soapy water in the morning. Or fill cat food cans with 1/4 inch of oil (preferably fish oil) and sink them into the ground near plants. Empty them every day. Sprinkle a 2-inch-wide circle of diatomaceous earth around beds or the base of plants; reapply after rains. Place a light-colored cloth beneath an infested plant and shake or tap the branches. The earwigs should fall onto the cloth and can be disposed of. The earwig's only insect predator in North America is the tachinid fly. Attract this fly by planting alyssum, calendula, dill, and fennel.

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Description
A common garden pest, these glossy, flattened insects are brown to black in color and measure 1/2 to 1 inch long, and they have a pair of curved pincers or forceps emerging from the tip of the abdomen. Adults may or may not have wings, but rarely fly; they also rarely pinch. Larvae resemble adults. Found throughout North America, the European earwig (Forficula auricularia) is most problematic in northern areas; the ringlegged earwig (Euborellia annulipes) in the South.

Damage
Earwigs are omnivorous and primarily feed on decaying organic matter as well as some pest insects, including aphids and other insect larvae. They are beneficial in compost piles and as pest predators, but are a nuisance because they are attracted to moist areas around and inside homes. They become pests when they come indoors and when outdoor populations get out of control. In gardens and greenhouses, they chew irregularly shaped holes in plant leaves and flower petals, tunnel into flower buds, and also consume seedlings.

Life Cycle
Overwintering adults lay clusters of round, white eggs in the soil in late winter; larvae, which resemble adults, hatch in spring. Adults overwinter under garden debris, stones, and boards as well as in soil.

Control
Clean up garden debris and organic mulches, especially around foundations, since moist areas serve as daytime hiding spots for earwigs. Spread dry gravel as mulch next to foundations. Earwigs are attracted to lights, so eliminate or reduce lighting around foundations. To trap earwigs, set out crumpled, damp newspaper, lengths of old hose, or boxes with small holes cut in the sides and baited with oatmeal; collect and dump trapped pests in soapy water. Spread diatomaceous earth in limited areas where earwigs commonly travel, and repeat applications after rains; encourage tachinid flies, which are natural predators; apply the nematode Steinernema carpocapsae.

Photo: (cc) pondman2/Flickr

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