Earwigs

Earwigs

Earwigs
Order:	Dermaptera
Metamorphosis:	Incomplete
Damaging stages:	All, but often predatory as well as herbivorous

Earwig from Australia compared to a CF card - 63 mm

Female (cerci not hooked)

An earwig from the Western Ghats

Earwig is the common name given to the insect order Dermaptera. With about 1,800 recorded species in 10 families, the order is relatively small among Insecta. Earwigs are, however, quite common globally. There is no evidence that they transmit disease or otherwise harm humans or other animals, despite their nickname pincher bug.

Most earwigs found in Europe and North America are Forficula auricularia, the European earwig, which is distributed throughout the cooler parts of the northern hemisphere.

Description

Earwigs are characterized by membranous wings folded underneath short leathery forewings (hence the literal name of the order - "skin wings"). The abdomen extends well beyond the wings, and frequently, though not always, ends in a pair of forceps-like cerci.

The abdomen of the earwig is flexible and muscular. It is capable of maneuvering as well as opening and closing of the forceps. The forceps are used for a variety of purposes. In some species, the forceps have also been observed in use for holding prey, and in copulation. The forceps tend to be more curved in males than in females.

Most earwigs are elongate, flattened, and are dark brown. Some tropical species are brightly colored. Occasionally earwigs are confused with cockroaches because of their cerci and their long antennae. Lengths are mostly in the 10–14 mm range, with the St. Helena earwig reaching 80 mm. Cerci range from nonexistent to long arcs up to one-third as long as the rest of the body. As in other orthopteroid insects, mouthparts are adapted for chewing. When earwigs have wings (are not agnathous), the hindwings are folded in a complex fashion, so that they fit under the forewings. Earwigs rarely fly.

Earwigs are drawn to damp conditions. During the summer they can be found around sinks and in bathrooms. Earwigs tend to gather in shady cracks or openings or anywhere they can remain concealed in daylight hours. Picnic tables, compost and waste bins, patios, lawn furniture, window frames or anything with minute spaces can potentially harbour these unwanted residents. Upon gaining entry to the basement and living areas of the home, earwigs can easily find cover in undisturbed magazine and newspaper piles, furniture/wickerwork, base boards, carpeted stairways, pet food dishes, and even inside DVD cases. Earwigs are inclined to take risks and are exploratory creatures but are overly unaware of the consequences and will often find themselves trapped in poison baited cups or buckets of soapy water.

Host plants

Erwigs feed on other insects, plants, ripe fruit, and garbage. Plants they feed on typically include clover, dahlias, zinnias, butterfly bush, hollyhock, lettuce, strawberry, sunflowers, celery, peaches, plums, potatoes, roses, seedling beans and beets, and tender grass shoots and roots; they have also been known to eat corn silk, damaging the corn. Typically they are a nuisance because of their diet, but normally do not present serious hazards to crops.

Control

While earwigs can be considered in some ways a beneficial part of the garden, they can become a nuisance because of their diet.

• Trapping: Since they prefer cool, moist places, a rolled up damp newspaper placed where earwig activity is suspected can be effective in collecting them. The newspaper can then either be discarded or shaken out. Another method of removing earwigs is by utilizing their attraction to vegetable oil. Putting vegetable oil in a pie tin and burying it up to the rim of the tin is an effective way of capturing them.
• Repellents: Placing diatomaceous earth in key spots around the home (bathroom, baseboards, window frames) can be a long-term repellent.
• Biocontrols (microscopic): Spraying with commercially available insecticidal nematodes, which invade the earwigs in their nymphal stage and infect them with a lethal bacteria to control the population before they hatch

External links

• Tree of Life info for Dermaptera
• CSIRO Dermaptera page
• What's That Bug's Earwig Page
• Harvard University information on earwigs

References

• Grimaldi, David and Engel, Michael S. (2005). Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5.{{cite book}}: CS1 maint: multiple names: authors list (link)
• J. D. Taylor (1978). "The earwig: the truth about the myth". Rocky Mountain Medical Journal. 75: 37–38. {{cite journal}}: Unknown parameter |quotes= ignored (help)
• http://bugs.bio.usyd.edu.au/Entomology/externalmorphology/imagepages/cerci.html
• http://creatures.ifas.ufl.edu/veg/european_earwig.htm
• http://www.bartleby.com/65/ea/earwig.html
• http://www.cascadepest.com/pest.htm#earwigs
• http://www.islington.gov.uk/DownloadableDocuments/Environment/Pdf/pestearwig.pdf
• http://www.eartheasy.com/live_natpest_control.htm
• Harvard University fact sheet on earwigs