Earwigs

Overview

The primary earwig found in the Midwest is the European earwig, Forcifula auricularia, in the insect order Dermaptera. Although earwigs can be pests in their own right, they deserve more widespread recognition as beneficial predators. They are omnivores and feed on insects, detritus, fungi, and plants. They help control the common aphid as well as the other aphid species that attack apple, plum, pear, spirea, dogwood, flowering crabapple, and flowering quince, among others. While it is true that they may inflict minor damage in the garden, particularly to seedlings, their presence is generally far more beneficial than detrimental. The earwig's biggest problem seems to be one of image: its scary-looking pincers and a name which derives from an old Anglo-Saxon word meaning "ear creature" evoke unfounded fears dating back to old Europe, when they were first introduced. Nevertheless, while used as a defense mechanism against predators, the pincers are not a menace to people. 

These insects are generally nocturnal and tend to conceal themselves in dark, moist spaces during daylight hours. You are unlikely to see them in the garden except at night, when they do the bulk of their feeding. They are recognizable with their dark reddish-brown body and yellow-brown legs, as well as their elongated shape and characteristic forceps at the end of their 3/8" to 5/8" bodies. When disturbed, they may release a foul-smelling yellow-brown liquid from their scent glands. 

Symptoms & Diagnosis

Earwigs tend to damage seedlings, corn silks, and occasionally ornamental plants. Damage from earwigs often looks similar to slug or rabbit feeding, including chewed and irregular holes from leaves and flowers, and damaged or dead seedlings. Damage is distinguishable from slugs due to the absence of a slime trail. Conduct a nighttime check with a flashlight to determine if earwigs are indeed responsible for the damage in question before managing their numbers. 

Life Cycle

Most earwigs will produce a single generation in a year. Occasionally, in their more eastern range in the U.S., they will produce a second generation. They begin mating in the fall, and adult females will lay eggs between midwinter and early spring in a small chamber underground or in a crevice. The eggs hatch in about seven days during warm spring months, in which nymphs will emerge looking like a smaller and paler version of an adult earwig. Nymphs will undergo five to six instars, or molts, before reaching maturity. 

Integrated Pest Management Strategies

1. Mulch your garden. This will provide a complex soil surface with many organisms on which earwigs can feed and should prevent them from inflicting major damage on your plants.

2. Grow seedlings indoors and transplant them outdoors when they are large enough to sustain some damage.

3. Use traps. Unbaited bamboo tubes or rolled-up newspapers are good traps. Place any of these traps on the soil around dusk and check with a flashlight 12 hours later or the following morning. Shake trapped insects into a pail of soapy water to drown them.

Since earwigs have a preference for sweet and/or oily foods, a small container of oil submerged in soil to the rim can be used to trap insects. Place around plants or in areas of the garden where the insects are most damaging. 

4. Diatomaceous earth dusted at the base of the plant is useful. For serious infestations, the lower sides of stems and leaf undersides should also be dusted.

Organic Strategies

Strategies 1, 2, 3, and 4 are strictly organic approaches. 

Pesticide Disclaimer: 

Always follow the product's label and ensure the product is effective against slugs/snails. Not following the pesticide label before usage is a violation of federal law.