Earwig

The earwig is a predatory insect with omnivorous feeding habits that sometimes cause significant damage to some crops. Most often, they contaminate vegetables by climbing inside them. However, they can be useful in some cases due to their predatory habits. The name refers to the legend that it can crawl into a person's ear and gnaw through the eardrum. It is curious that such an explanation is also available in the English-speaking segment. However, no such cases have been recorded.

View origin and description

Photo: Earwig

Photo: Earwig

The earwig survives in a wide variety of environments and is a fairly common household insect. Today, the name earwig (in English earwig) is interpreted as referring to the appearance of the hind wings, which have features unique and characteristic of these insects and resemble a human ear when unfolded. The species name is a specific reference to this feature.

The earliest earwig fossils date back to the end of the Triassic period. A total of 70 specimens were found. Some anatomical features of modern earwigs are not found in the earliest fossils. Their claws were not fully bent, as in modern representatives. Ancient insects outwardly resembled the current cockroaches. Their trace was lost in the sediments of the Permian period. Representatives of this group have not been found in the Triassic period, when the evolutionary transition from Protelytroptera to earwigs may have occurred.

Video: Earwig

Archidermaptera is thought to be related to the remaining earwig groups, the extinct Eodermaptera group, and the living suborder Neodermaptera. Extinct suborders have tarsi with five segments (as opposed to the three found in Neodermaptera) as well as unsegmented cerci. No fossil Hemimeridae and Arixeniidae are known. Like most other epizootic species, there are no fossils, but they are probably no older than the Late Tertiary.

Some evidence for early evolutionary history is the structure of the antennal heart, a separate circulatory organ composed of two ampullae or vesicles that are attached to the frontal cuticle at the bases of the antennae. These features have not been found in other insects. They pump blood with elastic connective tissue, not muscles.

Appearance and Features

Photo: What an earwig looks like

Photo: What an earwig looks like

Earwigs are brownish-red in color and have oblong bodies 12 to 15 mm long. They are equipped with 3 pairs of yellowish-brown legs. The elongated flattened brownish body has a front back in the form of a shield. The insect has two pairs of wings and filiform antennae about 12–15 mm long. Adult males are diverse in body weight and head width. Common earwigs are known for a set of forceps that protrude from the abdomen and are used for defense and in mating rituals.

The forceps show sexual dimorphism, being stronger, longer, and more curved in males than in females. Female forceps are about 3 mm long, less durable and straight. The European earwig has two antennae, 14 to 15 segments long, which contain many important sensory organs, as well as a fully developed set of wings.

Long jointed filaments are used during mating, feeding and self-defense. Females also have a tegmena about 2 mm long. The hindwings are membranous, wide with lobed veins. The earwig is held almost vertically in flight. Folding the wings together, the insect folds them twice. Despite the rather developed wings, the earwig rarely uses them, preferring to move on its limbs. The legs are of a running type, consisting of three segments.

Where does the earwig live?

Photo: Earwig in Russia

Photo: Earwig in Russia

Earwigs are native to Europe, East Asia and North Africa. Today they can be found on every continent except Antarctica. The geographic range of the species continues to expand. They have even been found on the island of Guadeloupe in the Pacific Ocean. In Russia, the earwig has been seen east to Omsk and in the Urals, and in Kazakhstan, the range extends to the interfluve of the Volga, south to Ashgabat, including the Kopetdag mountains. The earwig was introduced to North America in the early twentieth century and is now distributed over most of the continent.

Interesting fact: In North America, the earwig has two related subspecies that are reproductively isolated. Populations in cold climates generally have one clutch per year, forming species A, while populations in warmer climates have two clutches per year, forming species B.

European earwigs — they are terrestrial organisms that live mostly in temperate climates. They were originally found in the Palaearctic and are most active when daytime temperatures have minimal fluctuations. The insects are found over a very large geographical range and at altitudes up to 2824 m. During the day, they prefer places that are dark and damp to hide from predators.

Their habitat includes forests, agricultural and suburban areas. During the mating season, females prefer a nutrient-rich habitat as a place to burrow and lay their eggs. Dormant adults can tolerate cool temperatures, but their survival rate is reduced in poorly drained soils such as clay. To avoid excessive moisture, they tend to the south side of the slopes. Sometimes they also occupy hollow flower stems.

What do earwigs eat?

Photo: Common Earwig

Photo: Common Earwig

Earwigs are active mainly at night. This insect is omnivorous, feeding on a variety of plant and animal substances. Although the predatory habits of the insect somewhat compensate by eating plant matter, sometimes they can cause significant damage to vegetables, fruits and flowers. Beans, beets, cabbage, celery, cauliflower, cucumber, lettuce, peas, potatoes, rhubarb and tomato are among the vegetable crops that are under attack. Although earwigs are considered scavengers and predators. They feed on their chewing mouthparts.

They are known to feed on:

  • aphids;
  • spiders;
  • larvae;
  • mites;
  • insect eggs.

Their favorite plants are:

  • white clover (Trifolium repens); );
  • dahlia (Dáhlia).

They also like to eat:

  • molasses;
  • lichens ;
  • fruits;
  • fungi;
  • algae.

These insects prefer to eat meat or sugar rather than natural plant material, although plants are the main natural food source. Earwigs prefer aphids to plant material. Adults eat more insects than young ones. Among the flowers, dahlias, carnations and zinnia are most often injured. Ripe fruits such as apple, apricot, peach, plum, pear and strawberry are sometimes reported to be damaged.

Although earwigs have well developed wings, they are excessively weak and rarely used. Instead, earwigs use human clothing, commercial goods such as lumber, ornamental shrubs, and even newspaper bundles as their primary mode of transportation. They often consume vegetables and animal matter in equal proportions.

Peculiarities of character and lifestyle

Photo: Earwig Insect

Photo: Earwig Insect

Earwigs are nocturnal. They hide during the day in dark damp places such as rocks, plants, in heaps, in fruits, flowers and similar places. They emerge at night to hunt or gather food. They — weak flyers and therefore move mainly by crawling and being carried by a person. Earwigs can be considered both solitary and colonial insects. During the mating season, females live alone, but in other months of the year they tend to gather in very large groups.

Earwigs are considered a subsocial species as they provide parental care for their children. When common earwigs feel threatened, they use their forceps as a defensive weapon. Adult earwigs release a pheromone that attracts other earwigs. The nymphs also release pheromones that encourage their mothers to care for them. The tongs are also used as a means of mating communication and display threatening behavior.

The nocturnal activity of earwigs depends on the weather. A stable temperature encourages activity, but extremely high temperatures are discouraged. High relative humidity inhibits movement, while higher wind speeds and greater cloud cover encourage earwig activity. They produce aggregation pheromone in their feces, which is attractive to both sexes and nymphs, and secrete quinones as protective chemicals from the abdominal glands.

Social Structure and Reproduction

Photo: Earwig in the garden

Photo: Earwig in the garden

Earwigs usually mate in September, after which they can be found underground in burrows. Courtship rituals involving tongs play a large role in the mating process. The males wave their tongs in the air while stroking and grabbing the female. However, forceps are not used in the actual mating process. If the female approves of the male's advances, he turns his belly into mating position and attaches himself to the female. During mating, the females move and feed with the male attached to her abdomen. Fertilization of the eggs takes place inside the female. Sometimes during mating, another male will come along and use his tongs to fight off the mating male and take his place.

Fun fact: Earwigs usually breed once a year from September to January. In late winter or early spring, females lay 30 to 55 eggs in a burrow dug in the soil. The offspring become independent two months after hatching and no longer need parental care. Earwigs reach sexual maturity at 3 months and can breed as early as the next season.

Females hibernate about 5-8mm underground with their eggs, guarding them and keeping them free of fungus and other pathogens by using your mouth. Males are expelled from the hole in late winter or early spring, and the female lays fertilized eggs. When the larvae hatch after 70 days, the mother provides protection and food by burping.

When they become nymphs of the second age, they appear above the ground and find their own food on their own. However, during the day they return to their burrow. Nymphs of the third and fourth instars live above ground where they develop to adulthood. Nymphs are similar to adults but lighter in color with smaller wings and antennae. As the nymphs progress from one age to the next, they begin to darken, the wings grow, and the antennae gain more segments. Between each stage of development, the young molt, losing their outer cuticle.

Natural enemies of the earwig

Photo: What an earwig looks like

Photo: What an earwig looks like

The earwig is preyed upon by several species of diptera (Diptera) as well as beetles (Coleoptera). Main Enemies — ground beetles such as Pterostichus vulgaris, Poecilopompilus algidus, wood beetle and Calosoma tepidum, and flightless beetles (Omus dejeanii). Other predators include toads, snakes, and some birds. The earwig has several different defense mechanisms used to avoid predation. These include the use of tongs as a weapon and the use of glands in the abdomen to release chemicals that give off a foul odor and act as a repellant to predators.

The best-known predators of earwigs include:

  • ground beetles;
  • beetles;
  • wasps;
  • toads;
  • snakes;
  • birds.

Earwigs are hosts for various parasitic organisms. They also serve as predators of other insect species such as aphids and some protists. Earwigs are important scavengers in the ecosystem, feeding on almost anything that is edible. Earwigs can help control aphid populations, thereby reducing the number of crops being destroyed by pests.

Because earwigs tend to hide in dark, damp places, they often enter homes. These insects are practically harmless to humans, but the unpleasant smell and appearance make them unwanted guests in the house. They can also harm fruits and other crops as they feed on them.

In addition, the earwig causes significant damage to crops, flowers, and orchards when populations are high. Some of the commercially valuable vegetables it feeds on include cabbage, cauliflower, celery, lettuce, potatoes, beets, and cucumber, among others. They readily consume corn panicles and can damage crops. They damage young plum and peach trees in early spring when other food is scarce, devouring flowers and leaves at night.

Population and species status

Photo: Earwig

Photo: Earwig

Earwigs are not endangered. Their numbers and range of distribution are constantly increasing. They are considered to be harmful insects, despite the fact that they destroy some pests. Earwigs are not well liked by people due to their unpleasant odor and annoying tendency to aggregate in or near human dwellings.

Biological methods have been used to control earwigs, including some of its natural enemies, such as Erynia fungi forficulae, the fly Bigonicheta spinipenni and Metarhizium anisopliae, and many bird species. Insecticides have also been successfully introduced, although these treatments are rarely targeted specifically at earwigs. Multipurpose insecticides to control earwigs, grasshoppers and other insects are more common.

Fun fact: Diazinon, an organophosphate insecticide, continues to kill earwigs up to 17 days after the initial spray.

The earwig is a natural predator of a number of other agricultural pests, including several aphids, and has been used to control pest outbreaks. The damage caused by F. auricularia to crops is limited, provided that the population of other insects is high. Therefore, people also seek to use F. auricularia in pest control.

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