Earwig

From New World Encyclopedia
Revision as of 20:00, 3 January 2009 by Rick Swarts (talk | contribs)
Earwig
Fossil range: Jurassic to Recent
Common earwig, Forficula auricularia
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, 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 suboders.

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.

Appearance and behaviour

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

membranous wings folded underneath short leathery forewings (hence the literal name of the order, "skin wings"), .

Most earwigs are elongated, flattened, and are dark brown. Lengths are mostly in the quarter- to half-inch range (10–14 mm), with the Saint Helena Giant Earwig reaching three inches (80 mm). Cerci range from nonexistent to long arcs up to one-third as long as the rest of the body. Mouthparts are designed for chewing, as in other orthopteroid insects. Flight capability in Dermaptera is varied, as there are species with and without wings. In those earwigs that have wings (are not apterous), the hindwings are folded in a complex fashion, so that they fit under the forewings. Most species of winged earwigs are capable of flight, yet earwigs rarely fly around.

Prognathism is a term used to describe the positional relationship of the mandible and/or maxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in the sagittal plane of the skull. I

Female (cerci not hooked).
An earwig from the Western Ghats
Common Earwig

The abdomen of the earwig is flexible and muscular. It is capable of 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. The forceps tend to be more curved in males than in females.

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.[1] 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.[2]

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".[3] 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: [4]

  • 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.

Notes

  1. Oxford English Dictionary on "Earwig".
  2. Fabian Haas, Dermaptera — Earwigs, Tree of Life web project 
  3. dictionary.com: earwig
  4. Susan M. Rankin and James O. Palmer (pp. 297-299) in Resh, V. H. & R. T. Cardé (Editors) 2003. Encyclopedia of Insects. Academic Press.

References
ISBN links support NWE through referral fees

External links

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.