Earwig

Earwigs are the insects, which belong to Dermaptera is the insect order that includes earwigs. They are amongst the smaller insect orders, with roughly 2,000 species divided into 12 families. Earwigs do have a set of forceps-like pincers on their abdomen and membrane wings folded behind short, rarely employed forewings, thus the scientific name "skin wings." Certain parasitic groups are microscopic and lack the characteristic earwig pincers. Except for Antarctica, earwigs can be found on every continent.

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Earwigs are primarily nocturnal, hiding in tiny, wet crevices during the day and preying on a range of insects and plants at night. Earwigs, particularly the common earwig Forficula auricularia, are widely blamed for harm to foliage, flowers, and other crops. Before becoming adults, earwigs go through five moults in a year. Numerous earwig species exhibit maternal behaviour that is unusual for insects. Female earwigs might look after their eggs, and even after their young have hatched as nymphs, they would keep an eye on them until their second moult. Sexual dimorphism, like changes in pincer forms, emerges after the nymphs moult.

Certain earwig fossils belong to the extinct suborders Archidermaptera or Eodermaptera, the former of which dates from the Late Triassic and the latter from the Middle Jurassic. Dermaptera is member of the Polyneoptera order, and its closest living relatives are the angel insects of the Zoraptera order.

Scientific Classification

The scientific name for the order, "Dermaptera," is derived from the Greek words derma, which means skin, and pteron (plural ptera), which means wing. Charles De Geer created the phrase in 1773. Earwig comes from the Old English words eare, which means "ear," and wicga, meaning"insect," or precisely "beetle." The name is thought to be derived from the look of the hindwings, which are distinct and unique amongst insects and represent a human ear when unfurled, according to entomologists. The word is more commonly associated with the old wives' tale that earwigs burrow into people' brains via their ears and lay their eggs there. Although earwigs are not believed to actively enter ear canals, anecdotal accounts of earwigs being discovered in the ear were reported.

Distribution

Earwigs could be seen throughout the Americas and Eurasia in large numbers. The common earwig was brought to North America from Europe in 1907, however, it is more prevalent in the southern and southwestern sections of the country. The spine-tailed earwig (Doru aculeatum) seems to be the only native earwig found in the northern United States. It could be seen as far north as Canada, hiding in the leaf axils of emergent plants in southern Ontario wetlands. Additional families, such as Forficulidae (which includes Doru and Forficula), Spongiphoridae, Anisolabididae, and Labiduridae, could be reported in North America.

In chilly climates, just a few earwigs survive the winter. In fields, forests, and gardens, they could be discovered in tight cracks. About 25 species are found in North America, 45 in Europe (including seven in the United Kingdom), and 60 in Australia.

Morphology

Typical earwigs have a flattened body with an extended body that is 7–50 millimetres (0.28–1.97 in) long. This permits them to fit into narrow crevices, including under bark. The Australian giant earwig (Titanolabis colossea) is the largest living species, measuring 50 mm (2.0 in) in length, whereas the potentially extinct Saint Helena earwig (Labidura herculeana) was 78 mm (3.1 in). 

The cerci, or pair of forceps-like pincers on an earwig's abdomen, distinguish males from females. Male earwigs have far more bent pincers than females. Such pincers have been used to catch prey, protect themselves, and wrap their wings underneath the tegmina, which is very short. The antennas have at least ten segments and are thread-like. The forewings are tiny, oblong leathery plates that, such as the elytra of a beetle, are employed to shelter the hindwings rather than to fly. The majority of species possess short, leathery forewings with quite thin hindwings, while species in the Arixeniina and Hemimerina suborders are wingless and blind, with filiform segmented cerci.

The hindwing is an extremely thin membrane, which spreads out like a fan from a point folded beneath the forewing. Despite the fact that most earwigs have wings and can fly, they are hardly seen doing so. The venation of these wings is distinctive, as is the folding pattern which necessitates the employment of the cerci.

Internal

Insects have a neuroendocrine system that is similar to ours. There are six abdominal ganglia, a subesophageal ganglion, three thoracic ganglia, a brain, and a subesophageal ganglion. The neurohemal corpora cardiaca is connected to the brain and frontal ganglion by strong neuron connections, and the closely similar median corpus allatum generates juvenile hormone III in close vicinity to the neurohemal dorsal arota. Earwigs have the same digestive system as the other insects, with a foregut, midgut, and hindgut, but they lack gastric caecae, which are specialised for digesting in several insect species. Between the mid-and hindgut junction, long, slender malpighian tubules could be seen.

The eggs leave the body through the lateral ducts, whereas sperm is kept in the spermatheca. The gonopore, or genital opening, is located behind the seventh abdominal segment, unlike in other insects. The ovaries are polytropic, which makes them primitive. Long ovarioles branch from the lateral duct in certain species, whereas short ovarioles from around the duct in many others.

Life Cycle and Reproduction

Earwigs are hemimetabolous, which means they have been through a sequence of 4 to 6 moults to finish their development. Instars are the developmental phases that occur between moults. From the time they hatch, earwigs live for about a year. They begin mating in the fall and could be found together throughout the fall and winter. The male and female would share a 2.5-centimetre-deep chamber in trash or soil. After mating, the sperm might stay in the female for months before fertilising the eggs. The male would leave or be pushed out by the female from midwinter to early spring. In two days, the female would start laying 20 to 80 pearly white eggs. Several parasitic earwigs, such as those in the Arixeniina and Hemimerina suborders, are viviparous, meaning they are nourished by a placenta.

The eggs are white or cream-coloured and oval-shaped when they are first deposited, but they have become kidney-shaped and brown just before hatching. Each egg measures about 1 mm (0.04 in) in height and 0.8 mm (0.03 in) in width. 

Earwigs are one of the few non-social bug species which care for their young.  Although studies have shown that the mother does not give heed to the eggs as she collects them, she does pay great attention to the requirements of her eggs, like warmth and safety. The mother could be seen picking up wax balls by accident, but they will be rejected since they lack the correct fragrance. The mother would also protect the eggs from predators, not allowing them to be eaten unless the clutch is unhealthy. Another feature of earwig parental care is that the mother needs to clean the eggs on a regular basis to keep them free of fungus. The need to clean the eggs lasts for days until they have been taken, according to studies; when the eggs were reinstalled after hatching, the mother cleaned them for up to three months.

In around seven days, the eggs will hatch. The nymphs' mother could help them hatch. The nymphs consume the egg case and stay with their mother after hatching. The nymphs have a similar appearance to their parents, but are smaller, and will nest beneath their mother's protection until their second moult. The nymphs eat the food that the mother regurgitates as well as their own moults. The nymphs might consume the mother if she dies until the nymphs are ready to depart.

The nymphs will moult into adults after five to six instars. The males' forceps will curve, whilst the females' would stay straight. They will also retain their native colour, which can range from light brown (as in the Tawny earwig) to midnight black (as in the Ringlegged earwig). The wings of winged earwig species would begin to form at this time. An earwig's forewings are sclerotized to provide shelter for the membranous hind wings.

Behaviour

The majority of earwigs are nocturnal and live in tiny cracks, consuming little amounts of material including bark and fallen logs. Blind species were discovered living in caves, or cavernicolous, on the Hawaiian island of Oahu and in South Africa. Food is made up of a diverse range of live and dead plant and animal components.

Earwigs of the species Doru taeniatum could shoot foul-smelling yellow liquid in the kind of jets from scent glands upon the dorsal side of the third and fourth abdominal segments to defend themselves from predators. It focuses the discharges by rotating its abdomen, a move that allows it to utilise its pincers in defence at the same time.

Ecology:

Earwigs are primarily scavengers, however, most are predatory or omnivorous. The earwig's abdomen is flexible and muscular. It has the ability to open and close the forceps and also manoeuvre. The forceps can be used for a number of things. The forceps were recorded in certain species being used to grip prey and for copulation. Male forceps are generally more curved than female forceps. 

The common earwig is an omnivore that feeds on plants, ripe fruit, and actively hunts arthropods. This species is mostly a scavenger, eating decaying plant and animal materials when given the opportunity. Plant lice are the most common prey, but huge insects like bluebottle flies and woolly aphids have also been seen. Clover, butterfly bush, zinnias, dahlias, lettuce, potatoes, hollyhock, grapes, roses, strawberry, blackberry, cauliflower, celery, sunflowers, plums, peaches, seedling beans and beets, and tender grass shoots and roots are among the plants they eat; they have indeed been made to consume corn silk, causing damage to the corn.

Predators and Parasites

Birds commonly hunt on earwig bugs, and they are also prey for insectivorous animals, lizards, amphibians, assassin bugs, centipedes, and spiders, as do most other insect species. Bats were being spotted feasting on earwigs by European naturalists. Tachinidae, or tachinid flies, are their major insect predators, and their larvae are endoparasites.

For nearly a century, a single species of tachinid fly, Triarthria setipennis, has been shown to be effective as biological control of earwigs. Ocytata pallipes, a tachinid fly and earwig parasite, has also shown potential as a biological control agent. When earwigs are plentiful, the yellow jacket (Vespula maculifrons), a typical predatory wasp, preys on them.

Mermis nigrescens, a small roundworm, has been reported to parasitize earwigs that had swallowed roundworm eggs with plant materials. On earwigs, at least 26 parasitic fungus species from the order Laboulbeniales have been discovered. Other earwigs will eat the eggs and nymphs as well. Histiostoma polypori (Histiostomatidae, Astigmata), a tyroglyphoid mite, has been seen on common earwigs in large numbers; however, this mite survives on earwig cadavers rather than live earwig prey. Scarlet acarine mites were discovered on European earwigs by Hippolyte Lucas.

Certain Other Types of Earwig:- Few types of earwigs may include black pincher bug, Maritime earwig, Albino earwig, Common earwig and others.

Maritime Earwig- Anisolabis maritima, often known as the maritime earwig or seaside earwig, is an earwig species belonging to the Anisolabididae family. This species, like the Seaside Earwig, can be found near the shore and is worldwide. It could be found practically everywhere in the biogeographic domain. These earwigs are thought to have originated in Asia, according to scientists. They were, however, brought to North America and have so far spread over the world as a result of international trade.

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This earwig is brownish or blackish in colour with pale yellow legs and measures 2.5 to 3 cm (1.0–1.2 in) in length. It does not have wings, unlike some other earwig species. Male coastal earwigs are notable for their distinctively asymmetrical forceps, which they employ for mating, catching prey, and self-defence. Such forceps have even been reported to be capable of breaking human skin.

Fleas, small beetles, ants, crickets, and sowbugs are among the small invertebrates preyed upon by this species, which also has cannibalistic tendencies. Maritime earwigs are frequently spotted behind seaweed and driftwood during the day due to their seashore setting. They love to stay in "dark, warm, damp locations."

Common Earwig: The common earwig, often known as the European earwig, is an omnivorous insect belonging to the Forficulidae family. The European earwig is a common household insect in North America that can thrive in a variety of conditions. The name earwig originates from the appearance of the hindwings, which are unusual within insects and look like a human ear once unfolded; the common earwig's species name, auricularia, is a connection to this trait. They are classified as a domestic nuisance because of their proclivity for entering home crevices and consuming pantry items and based on the location, they can act as a pest or a useful species.

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The reddish-brown body of Forficula auricularia is flattened and elongated, with thin, beaded antennae. The pair of 'pincers' or forceps at the apex of the flexible abdomen is a distinguishing feature of an earwig. Such pincers are present in both sexes; males' pincers are big and curled, whereas females' pincers are straight. Nymphs are identical to adults in appearance, but they lack or have little wings.