Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES
Earwigs
Adult European Earwig
Female & Male
Earwigs may cause alarm to homeowners when
discovered indoors. They have a frightful appearance, move rapidly around
baseboards at the ground level, and may emit a foul-smelling, yellowish-brown
liquid from their scent glands. These creatures, active at night while hiding
during the daytime, normally live outdoors and do not establish themselves
indoors. They are harmless to humans and animals, although if handled
carelessly, the earwig can give a slight pinch with the forceps: Serious
feeding damage may occur on flowers, vegetables, fruits and other plants,
giving the leaves a ragged appearance with the numerous, small, irregular
holes. Also, decomposing organic matter is consumed. They are considered
temporary pests in spite of the fact that they sometimes occur in large populations.
Identification
Earwigs are elongate,
flattened insects, ranging from light red-brown to black and are easily
recognized by their forcep-like appendages (pincers)
on the end of the abdomen. The forceps (cerci) are unequal in length in the
males. Earwig female forceps are straight-sided; whereas male forceps are
strongly curved (caliper-like} and larger. They have chewing mouthparts and
long, slender antennae and are either winged or wingless. If wings are present,
the first pair are hard, short and "beetle-like," while the second pair
are membranous fan shaped and folded under the hard first pair of wings. Tips
of the second pair of wings usually protrude from under the first pair. The
European earwig ranges from 1/2 to 3/4 inch long; with banded legs and reddish
head. The ring legged earwig ranges from 1/2 to 3/5 inch long and is
black-yellowish underneath with legs having dark cross bands. Young earwigs
(nymphs) are similar to adults. They are white to olive-'green and lack wings.
Life Cycle and Habits
The name earwig is derived from a European
superstition that these insects enter the ears of a sleeping person and bore
into the brain. This belief is totally unfounded. -Earwigs develop from egg to
adult through gradual metamorphosis with four to five nymphal
instars or stages. During the spring or autumn females lay 20 to 50 smooth,
oval, pearly-white or cream-colored eggs in a below-ground chamber (upper two
to three inches of soil). The female moves, cleans, and provides maternal care
by protecting the eggs and new young until the first molt. Young then leave the
nest, fend for themselves and mature in one season. Both eggs
and adults over winter. Earwigs may dig as deep as six feet below ground
to escape the cold temperatures. They are active at night and are often found
around lights. During the day, they hide in moist, shady places beneath stones,
boards, sidewalks and debris. They are rapid runners and feed on mosses,
lichens, algae, fungi, insects, spiders and mites, both dead and alive. Some
earwigs are predators, feeding on aphids and others feed on living plants,
becoming pests in greenhouses and on certain crops such as vegetables, fruits,
ornamentals, forages and field plants.
Earwigs rarely fly and are unable to crawl long
distances, but often hitchhike in laundry baskets, cut flowers, luggage,
newspapers, lumber, baskets of fruits and vegetables, automobiles, etc. They
prefer moisture and may migrate indoors during periods of prolonged heat and drought.
Forceps at the end of the abdomen are used to defend the nest, capture prey,
probe narrow crevices and fold or unfold wings.