Earwig

Earwig Fossil range: Jurassic to Recent
Common earwig, Forficula auricularia
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Hexapoda Class: Insecta Order: Dermaptera De Geer, 1773
Suborder
Archidermaptera † Forficulina Suborder Hemimerina Suborder Arixeniina

Earwig is the common name for any of the insects comprising the order Dermaptera, characterized by chewing mouthparts, incomplete metamorphosis, membranous wings folded underneath short leathery forewings (tegmina), and an abdomen that extends well beyond the wings, and frequently, though not always, ends in a pair of forceps-like structures termed cerci. The order is relatively small among Insecta, with about 1,800 recorded species placed into three extant and one extinct suborders.

Earwigs are quite common globally.

There is no evidence that they transmit disease or otherwise harm humans or other animals, despite their nickname pincher bug.

Appearance and behavior

Two earwigs from Australia compared to a CF card—63 mm.

Although the suborders Hemimerina and Arixeniina are comprised of species that are wingless, as are some of the large suborder Forficulina (Von Ellenrieder 2004), earwigs typically are characterized by two pairs of wings on the thorax. Of these, one pair is membranous wings and is folded in a complex manner underneath short leathery forewings. The small pair of leathery forewings is called tegmina, and they cover only the first segments of the abdomen and leave the posterior of the abdomen exposed. The small, leathery tegmina give rise to the ordinal name of the order, Dermaptera, with the name Derma meaning "skin," and ptera meaning "wings" (hence "skin wings") (Von Ellenrieder 2004). Most species of winged earwigs are capable of flight, yet earwigs rarely fly around.

Most earwigs are elongated, flattened, and are dark brown. Lengths are mostly in the quarter- to half-inch range (10 to 14 millimeters), with the Saint Helena giant earwig reaching three inches (80 millimeters). Antennae are thin, long, and filiform (Von Ellenrieder 2004). Mouthparts are designed for chewing, as in other orthopteroid insects.

Female (cerci not hooked).

An earwig from the Western Ghats

Common Earwig

The abdomen of the earwig is flexible and muscular. There typically is an unsegmented, pincer-like cerci at the posterior end, which usually is straight in females and curved or asymmetrical in males (Von Ellenrieder 2004). Cerci range from nonexistent to long arcs up to one-third as long as the rest of the body. The cerci in the suborders Hemimerina and Arixeniina is filamentous (Von Ellenrieder 2004).

The flexible abdomen allows maneuvering as well as opening and closing 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.

Most earwigs found in Europe and North America are of the species Forficula auricularia, the European or common earwig, which is distributed throughout the cooler parts of the northern hemisphere. This species feeds on other insects, plants, ripe fruit, and garbage. Plants that they feed on typically include clover, dahlias, zinnias, butterfly bush, hollyhock, lettuce, cauliflower, strawberry, sunflowers, celery, peaches, plums, grapes, 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. Some tropical species are brightly colored. Occasionally earwigs are confused with cockroaches because of their cerci and their long antennae.

Earwigs are generally nocturnal and can be seen patrolling household walls and ceilings. Interaction with earwigs at this time results in a defensive free fall to the ground below, and the subsequent scramble to a nearby cleft or crevice.

Earwigs are also 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 that they can remain concealed in daylight hours. Picnic tables, compost and waste bins, patios, lawn furniture, window frames, or anything with minute spaces (even artichoke blossoms) can potentially harbor 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 and keyboards. Earwigs are exploratory creatures and are often found trapped in poison baited cups or buckets of soapy water.

Etymology

Earwig is derived from Old English ēare "ear" and wicga, "insect". (Wicga is in turn related to wiggle, and ultimately to other words implying movement, including way and vehicle, all from PIE *wegh-.) The name comes from the old wives' tale that earwigs burrow into the brains of humans through the ear and therein lay their eggs. Earwigs are omnivores that are predisposed to hiding in warm humid crevices and as such one may crawl into a human ear canal. This is not, however, a location where they are frequently found.

Other languages have words based on the same premise: German Ohrwurm (also: Ohrkneifer, "ear pincher"), French perce-oreille, Danish ørentviste, Slovak ucholak (ucho = ear, lak = scare), and Hungarian fülbemászó ("crawler-into-the-ear"). English has derived a verb from this, to earwig, meaning "to fill someone's mind with prejudice by insinuations" or "to attempt to influence by persistent confidential argument or talk". The German word Ohrwurm has the derived meaning "an annoying tune which I can't get out of my head" (see earworm). Hungarian also uses the phrase fülbemászó dallam with similar meaning as the German above, although without the negative overtones.

Classification

Four suborders within the Dermaptera have been established:

• Archidermaptera: Has a fossil record extending into the Jurassic, with fossils from that period. These have unsegmented cerci and tarsi with 4-5 segments.
• Forficulina: The largest and most familiar group. The cerci are unsegmented, and modified into large, forcep-like structures.
• Hemimerina: Represented by one genus, Hemimerus, with filiform segmented cerci and are wingless, blind and viviparous ectoparasites of African rodents
• Arixenina: Represented by two genera, Arixenia and Xeniaria. As with Hemimerina, they are blind, wingless ectoparasites with filiform segmented cerci. They are ectoparasites of various Southeast Asian bats, particularly of the genus Cheiromeles (i.e., "naked bulldog bats").

Pygidicranidae

Diplatyidae

Anisolabididae

Labiduridae

Apachyidae

Labiidae

Chelisochidae

Forficulidae

Suborder Hemimerina

Hemimeridae

Suborder Arixeniina

Arixeniidae

Pest control

Earwigs can be considered in some ways a beneficial part of the garden, especially when they prey on other insects, but they can become a nuisance because of their habit of positioning themselves within leaves and feeding on soft plant tissues. They prefer cool, moist places, and 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. Placing diatomaceous earth in key spots around the home (bathroom, baseboards, window frames) can be a long-term repellent.

References

ISBN links support NWE through referral fees

Von Ellenrieder 2004

• Grimaldi, D. and Engel, M.S. (2005). Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5. 
• Engel, M.S. and F. Haas (2007). Family-group names for earwigs (Dermaptera). American Museum Novitates 3567: 1–20.
• J. D. Taylor (1978). The earwig: the truth about the myth. Rocky Mountain Medical Journal 75: 37–38.
• Rod Serling's episode of Night Gallery, "The Caterpillar
• Weems Jr HV, Skelley PE. (1998). European earwig, Forficula auricularia Linnaeus. Featured Creatures. EENY-32. http://creatures.ifas.ufl.edu/veg/european_earwig.htm (31 July 2008).
• Pest Organisms of the Puget Sound Region: Earwigs, Cascade Pest Control 
• Keep earwigs away, Islington Council 
• Natural Insect Pest Control, eartheasy.com 
• Earwig Fact Sheet and Gallery, Harvard University 

External links

• Tree of Life info for Dermaptera
• CSIRO Dermaptera page
• "Earwigs eat through your brain" urban legend debunked
• What's That Bug's Earwig Page
• Harvard University information on earwigs
• Earwig Research Centre
• BBC Science and Nature Wildfacts
• ringlegged earwig on the UF / IFAS Featured Creatures Web site

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