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Description
The name earwig comes from a superstition that the insects
would enter the ears of a sleeping person and tunnel into
the brain. Fortunately, this is not true. Earwigs are not
a major pest; however they do feed on flowers and can be a
nuisance inside homes. Unusually wet springs and summers tend
to intensify earwig infestations. There are approximately
22 species of earwigs in the USA. The major earwig species
in the northern region of the USA is the European earwig,
Forficula auriculari.
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Figure 1. Earwig
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Figure 2. Earwig Nymph
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Adults
are pale-brown to reddish-black in color. They are 1/4 to
1.0 inches long and the body appears flattened. The front
wings are short and meet in a straight-line down the back.
The hind wings are membranous and folded underneath the front
wings. Both the males and females have large, pincers (cerci)
that stick out from the back of the abdomen. The pincers are
used in defense for protection against predators or to capture
prey. Earwigs resemble rove beetles, but rove beetles do not
have cerci.
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Life
Cycle
Earwigs hibernate in the soil as adults during the winter. In spring,
adult females lay 30 to 55 eggs in the soil. The females nurture
and protect the eggs and young (maternal care), which is uncommon
for insects. The eggs hatch into young nymphs. Earwigs have four
to five nymphal stages before becoming adults. Earwigs are nocturnal,
hiding during the daytime and active at night. They tend to prefer
moist environments. During the day, they usually inhabit dark confined
or shaded areas such as underneath plants, debris, stones, organic
mulch, tree bark, and flower pots. They are less likely to be found
in exposed sunny areas.
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Damage
Earwigs will enter homes to hide, but they don't breed because
the eggs and nymphs cannot tolerate long periods of dryness
(low humidity). When inside homes, earwigs may be mistaken
for cockroaches, as they tend to resemble each other when
it is dark. They generally occur in groups and once inside
a home they will feed on crumbs of human food as well as cat
and dog food. Earwigs are attracted to outdoor lighting.
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Figure
3. Earwig Adult
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Earwigs
feed on a wide range of food sources. They will eat aphids, mites,
and insect eggs. However, they also feed on the flowers of plants
including marigolds, petunias, dahlias, and hostas. Earwigs will
eat small holes in plant leaves and flowers during the night. Leaves
and petals have a ragged appearance with irregular-shaped holes.
Seedlings and flowering plants can be severely damaged or killed
by high earwig populations. Earwigs also eat pollen, fungi, and
lichens.
Management
Earwig management includes sanitation, modification of cultural
practices, trapping, or the use of pest control materials. Remove
outdoor harborage such as firewood, plant debris, weeds, and organic
mulches from around the foundation of a house or building. This,
along with caulking foundation cracks and crevices, will minimize
entry into homes. Avoid overwatering plants and don't use thick
organic mulches. Inorganic mulches such as lava rock or stone are
less attractive to earwigs. A moistened rolled-up newspaper, old
tuna fish can, or an eight to ten inch section of garden hose can
be used to trap earwigs. Place traps in shaded areas where earwigs
are most likely to hide during the daytime. Check traps in the morning
and shake the insects into a pail of soapy water. Granular or wettable
powder formulations of insecticides may be used to control earwigs
outdoors. Do not apply insecticides directly onto flowers, especially
those that are toxic to bees. For best results, apply insecticides
late in the afternoon or early evening, when earwigs are active.
To prevent earwigs from entering homes, caulk cracks and crevices
and weather-strip doors. Earwigs that accidentally invade home are
primarily a nuisance because they don't cause damage or reproduce.
Sweep or vacuum up earwigs that do enter the home. Chemical treatments
inside the home are generally not necessary.
Prepared
by Raymond A. Cloyd, Department of Natural Resources and Environmental
Sciences, University of Illinois, Urbana, Illinois, in cooperation
with the Illinois Natural History Survey. For additional copies,
contact your local University of Illinois Extension Office.
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