The common earwig (Forficula auricularia) is an insect of the order Dermaptera. It is characterized by presenting a pair of appendages on the back of the abdomen in the form of pincers or scissors, an elongated, flattened body and with three pairs of legs. Its coloration is dark reddish brown and can reach up to 25 mm long.
It is a species that is found in humid environments and has twilight and nocturnal habits. It can be found under litter and rocks, in wall crevices, and under vases, among other places. It is native to Europe, West Asia and North Africa and has been accidentally introduced into the American continent.
The common earwig is omnivorous, it feeds on anything, for example living or dead plant material, flowers, fruits, leaves, shoots, grains. It can also feed on other insects, living or dead, and can even feed on insects of the same species (cannibalism).
It is a species considered a pest in some regions, where it can cause significant damage to orchards and gardens. It can also live indoors, causing tissue damage and contaminating food by walking on top of it and depositing its feces..
Its appearance is threatening due to the presence of the scissors or pliers (fences), however, these structures are intimidating organs because they do not have poison or great strength to serve as an offensive weapon..
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The common earwig is an insect with an elongated body and dorsoventrally depressed, with an average length of 12 to 15 mm, but which can reach up to 25 mm. The head is provided with a pair of antennae with 14-15 knuckles, shorter than the length of the body, and underdeveloped chewing mouthparts..
The pronotum is shell-shaped. The thorax has three pairs of legs in addition to two pairs of wings. The wings are well developed, but do not cover the abdomen. The body is reddish brown and the legs are lighter than the body.
The abdomen is visible dorsally, ending in a pair of appendages in the form of forceps or scissors that are called fences. The length of the abdomen with enclosures included, exceeds the length of the thorax and head together. The fences are sexually dimorphic, longer, robust, curved and crenulate in males; short, straight and smooth in females.
Polymorphism is also observed in males, with some specimens more robust and with more developed fences than others..
According to some authors, the species has 4 nymphal stages while others maintain that there are actually 5. The nymphs are similar to adults, but lighter in color and their wings and fences are reduced or absent. The wings develop from the 4th nymphal stage. Body color darkens with each change.
The antennae of the first and second nymph have 8 segments, then this number will be increased to 12 segments in the last nymph stage.
Each egg has an elliptical to oval shape and is white or slightly yellow in color. At the time of the laying it measures 1.13 mm long by 0.85 mm high and its size increases as the moment of hatching approaches.
The female can lay more than 60 eggs in shallow galleries built into the ground..
Forficula auricularia It is a terrestrial species that prefers humid and temperate climates, not supporting well the lack of humidity. Its optimum growth temperature is 24 ° C. Its habitat includes forests, agricultural and sub-agricultural areas. It is found in areas where there is no direct incidence of the sun's rays, such as leaf litter, under rocks or logs.
Under normal conditions they are far from the houses unless there are excessively large populations or the environmental conditions are not very favorable. In the southernmost areas of the American continent they are frequent in nurseries, greenhouses and other agricultural structures..
During the reproductive season, the female prefers rich and well-drained soils, as she burrows in them to deposit her eggs. In houses they can be hidden under vases, cracks in walls and trash cans..
The species is cosmopolitan and its original distribution includes Europe (except the northernmost part of Scandinavia), East Asia and North Africa, although it is currently easily traceable globally..
Altitudinally it can be distributed from sea level to more than 2824 m in height. It has nocturnal and twilight habits and remains hidden during daylight hours in dark areas, under weeds, rocks, leaves, in screams, etc..
It usually aggregates in large groups, except in the reproductive season, when the female isolates herself to care for and protect her offspring..
The common earwig is an insect of the order Dermaptera included in the family Forficulidae. This family is divided into four subfamilies and a large group of species whose taxonomic location is uncertain (Incertae sedis). The gender Forficula, which was proposed by Linnaeus in 1758, is included in the subfamily Forficulinae.
According to some authors, representatives of the species Forficula auricularia they could really be a complex formed by two sibylline species, one of which would be distributed in northern Europe and the mountainous regions of southern Europe, while the other would be inhabiting the lower areas in southern Europe.
The common earwig is a species of sexual reproduction, with separate sexes (dioecious) and sexual dimorphism. Males are larger and have larger and more arched fences, while females are rectilinear and smaller. During the reproductive season, the female produces and secretes pheromones that attract the male..
Prior to copulation, the males of Forficula auricularia they must perform a courtship ritual in which fences play an important role. The males wave the fences in the air and touch the female with them. If the female accepts the courtship of the male, he arches his abdomen below that of the female and positions him for copulation..
During copulation the female can move and feed with the male attached to her abdomen. Fertilization is internal. During copulation a male can confront the one who is copulating with the female and displace him to take his place. Both males and females can carry out the sexual act with different partners.
The fertilized female lays about 50 eggs (although sometimes they can be more than 60) in a shallow gallery built in the ground, and performs parental care of them, cleaning their surface with her mouth to protect them from parasitic fungi. After about 70 days after laying, the nymphs hatch.
The female continues to care for the young by regurgitating the food to feed them. After the first molt, the nymphs emerge from the gallery and are able to get their own food. Females can sometimes lay a second group of eggs during the same reproductive period..
The species goes through 6 nymph stages in a period of 56 days and matures sexually, being able to reproduce in the next reproductive season..
Forficula auricularia it is an omnivorous species, with chewing-type mouthparts. It feeds on other organisms, both animals and plants, living or decomposing. In adverse conditions you can also practice cannibalism. The species is especially voracious in the later nymph stages.
The plant diet of this species includes lichens, algae, flowers, fruits, leaves, shoots and even seeds. Drill small, deep holes in the fruit. In homes it can cause damage to plants and their flowers and in nurseries it can cause considerable damage in various fruit and vegetable productions.
Regarding their carnivorous habits, their main prey are aphids, worms, spiders and protozoa. It is a voracious predator of these organisms in their natural environment, exerting control over their populations..
When the earwig feels threatened, it raises the bottom portion of the abdomen as a deterrent to a potential predator. However, despite their dangerous appearance, these fences are not poisonous and their bite is not harmful, resembling rather a pinch..
There are no serious side effects or consequences from the insect bite. More damaging is its allergenic effect on some people. Allergic reactions can arise from direct contact with the animal by consuming food contaminated with its feces or by inhaling remains of the exoskeleton or the feces of the insect.
In its natural environment, the common earwig feeds on a wide variety of insects and other arthropods, including aphids, which are phytophagous organisms that cause serious losses in the crops of some fruit trees, mainly apple and pear trees..
Due to this, many European farmers try to guarantee the presence of earwigs in their crops, increasing the number of places where they can hide and minimizing the use of pesticides that can affect them..
Additionally, there are management plans for the species to increase its populations in the event of the presence of an aphid plague. Common earwigs cause significant declines in pest insect populations, reducing or avoiding the use of pesticides.
After the aphid population has decreased, Forficula auricularia persists without causing significant damage to plants.
In monitoring programs for aphid control Eriosoma larigerum affecting apple orchards in Australia, the researchers found that the use of the common earwig, alone or in combination with other biocontrollers, was even more effective than the use of chemical agents, since the aphids developed resistance against them..
Despite being beneficial in their natural environments when controlling pest organisms, Forficula auricularia it can become a pest in environments where it has been introduced due to the absence of its natural enemies. Earwig infestations, however, are rare.
Very abundant populations of this species can cause significant damage in greenhouses as well as in gardens, attacking tender shoots of plants, fruits and even flowers..
In agricultural production centers where they become pests they can cause holes in the fruits that can then be colonized by other pathogens, devaluing the product. They can attack lettuce, strawberries, roses, among other plants, causing significant economic losses.
In the Falkland Islands they have become a significant plague that not only causes damage to gardens and greenhouses, but has even invaded hospital care centers, being able to seek shelter in inhalers and oxygen masks, causing additional security costs to ensure that these equipment is suitable for use.
There are different ways to try to solve the problems caused by common earwig pests, such as habitat management, use of pesticides, and use of biocontroller organisms..
Among the cultural practices for the prevention of the common earwig infestation, agricultural producers use the cleaning of weeds, debris and other objects or structures that can serve as a refuge for the insect in the growing area and in the vicinity of it..
Repellants, such as kerosene, or beer and yeast baits, are also used to ward off insects or lure them into traps where they will drown..
There are no specific pesticides to act against Forficula auricularia, for which the use of non-specific chemicals is necessary, which are generally very toxic and polluting.
Among the most widely used pesticides are pyrethroids such as permethrin and cypermethrin, methamidophos and dimethoate. All of them act by contact or by ingestion and range from moderately toxic to very toxic for humans..
In its natural environment, the common earwig has numerous enemies that maintain control over its populations. Among the species that prey on Forficula auricularia There are several species of flies of the family Tachinidae, such as Triarthria setipennis Y Ocytata pallipes.
Some beetles Pteros-tichus vul-garis, Carabus nemoralis Y Calo-soma tepidum, mushrooms Erynia forficulae Y Metarhizium anisopliae as well as spiders, birds, toads and snakes can feed on the common earwig.
Among these species, tachyinid flies have been introduced as biological controllers in areas where the common earwig was not found before and in which it is now considered a pest..
For example, Triarthria setipennis it was actively introduced in the Mediterranean area, several states of the United States of North America and in Canada, managing to establish itself in some of these localities. Recently a planting project of T. setipennis Y Ocytata pallipes in the Falklands to fight the common earwig.
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