What is the gadfly, lifestyle
The insect gadfly is a representative of parasitic flies from the family of Diptera, which live exclusively near humans or other large mammals, since they use a specific breeding method.
Biological description of the gadfly
There are more than 50 types of gadfly in the world, but only one of them is capable of harming a person by attacking him — this is human skin (Dermatobia hominis), which lives only in South America (see photo of gadfly).
Outwardly, the human gadfly is very similar to a black fly, but with a yellow head, orange paws and large eyes, its size reaches 12-18 mm. In the forests of Mexico, Argentina and other countries of Central and South America, local residents call this gadfly dangerous for humans differently: “green yellow-legged fly”. The disease he causes is called dermatobiosis. Infected people can spread such a disease to other countries.
Gadfly - an insect with large eyes, having a shaggy torso of 13-17 mm in size and translucent light wings. Thanks to the huge facet eyes iridescent with all the colors of the rainbow, the gadfly looks very original.
The peculiarity and danger of such an insect is in the peculiarities of reproduction, because it uses the body of mammals for carrying the offspring: livestock, horses, and sometimes humans. Very often in place bite big gadfly inflammation develops, which requires the intervention of a doctor or surgery.
Gadfly lives almost all over the world, except Antarctica, but prefer warm and temperate climatic zones. In Russia, gadflies are found mostly in southern and temperate latitudes; they attack livestock or wild animals in the forest.
There are deer, horse, stomach, sheep and other types of gadfly, which differ in the mammal in which the skin to such flies lay eggs.
Not all species of gadfly make laying after a bite, some attach eggs to the animal's fur or grass so that it will be eaten by the cattle. Another original way is to lay the larvae with a small gadfly on the back of a mosquito, which is carried out right in flight.
Gadflies are full-conversion insects that go through the entire development cycle from the egg through the larva, pupa and imago phases. The life cycle lasts a whole year. Moreover, adults do not have the ability to feed, but exist, thanks to previously accumulated substances in the body in the larval stage.
How many gadflies live depends on the temperature of the air and how quickly the insect can attach its progeny. Females try to choose a suitable place on the skin of the victim, where there is less wool, attaching several eggs to each hair. On average, the life expectancy of imago is 3-20 days.
To answer the question of where the gadflies come from, it is necessary to consider all phases of the development of the insect.
The life cycle consists of several periods and stages:
- The first stage larvae develop inside the laid eggs for several days (the speed of development depends on the temperature), and then begin to invade the host's body. Some gradually penetrate into the blood vessels, then move to the spine and reach adipose tissue along the spinal canal, others move closer to the esophagus to settle in its mucosa.
- The larvae of the 2nd and 3rd stages migrate further to the zone of the back and lower back of the animal; here they form capsules of connective tissue. For the subsequent development they need access of oxygen from the atmosphere, so they make moves directly in the skin of the host, called fistulas. Later, they molt, after the completion of the 3rd stage, the already ripe larvae go out through the holes and, leaving their capsules, fall to the ground, then pupation begins.
- A pupa is a phase that occurs within 1–7 days after larvae fall out from fistulas on the host’s skin; the pupation rate and development of the pupae depend on the temperature and humidity of the environment and lasts 33–44 days.
- The emergence of adult individuals (imago) from the pupae occurs in a few seconds, and the fly that has appeared is ready for mating and can fly.
Since the life of the gadfly is very short, the gadflies do not fall asleep in the fall (this is a common misconception) - adults die. The winter period is experienced by little faces in the body of its master.
Varieties of gadflies
Gadflies differ in the type of animal on which they lay their eggs and in the place where they are laid.
This species (Hypoderma bovis) is also referred to as a striped or bovine gadfly, since the female makes laying on the fur of the extremities of cattle (cows, bulls, etc.). After exiting the shell, the larva easily bites through the skin at such a place and moves to the tissues of the esophagus, then the back, resulting in the creation of large sores on the body of the animal. Through such nodules, air is supplied to the larvae spiracles, and they find food by pulling substances from the surrounding tissues.
After maturation, the larvae of the striped gadfly fall down from the nodule and pupate on the ground in order to turn into an adult fly after a certain time. All these actions cause pain and anguish for their victim, who has holes in her skin, which makes her depreciate.
On a note!
There are cases when gadfly larvae settled in the human body and even in the eyes, which led to great health problems. To remove the larvae from the eye has to resort to surgery.
Gastric insects (lat. Gasterophilidae), which includes horse gadfly, parasitizes donkeys and horses. This insect is yellow-brown in color, covered with yellow hairs, abdomen is yellow-black, gadfly size is 13-16 mm. The wings are covered with small dark spots.
The fly of the gadfly (photo below) lays eggs on the fur in the area of the head, legs of the animal or on plants intended for feed. After maturation, the larvae begin to feed actively, moving along the digestive tract, from which they are then released along with excrement.
On a note!
While moving, the gadfly larvae make moves, puncturing the skin in several places, which gives the owner unpleasant sensations of itching. As a result of parasitizing them in the stomach, the victim often develops catarrhs or other diseases of the digestive system.
Representatives of this species are insects:
- sheep gadfly (Oestrus ovis), which uses for breeding the wool of domestic sheep or goats;
- Russian or Russian gadfly (Rhinoestrus purpureus) - parasitizes donkeys and horses.
Cavity gadflies relate to viviparous insects in which females are able to give birth to larvae and in the process of flight spray them into the eyes and nostrils of an animal or person. Their development continues in the skin of the eyelids, on the mucous membranes of the nasopharynx or eyes, and even inside it, for which they are also called nasopharyngeal gadflies. When the larva moves inward into the head, they settle in the areas of the frontal or nasal sinuses, in the pharynx or ethmoid bone.
On a note!
Gadfly larvae feed on surrounding soft tissues for 3–9 months. Scientists attribute this type of insect to endoparasites that can cause various diseases.
One of the representatives of the abdominal species is the deer gadfly or the northern subcutaneous, which massively lays the larvae under the skin of animals. With multiple holes in the skin, deer often lose strength, and weakened ones simply die.
Mating and flying
Mating occurs almost immediately after its appearance from the pupa. Scientists note that during this period males live every year in the same place where they fly for mating. Then fertilized females begin to actively look for future owners for breeding.
The laying method depends on the type of female insect:
- The string usually flies over the herd of animals, emiting characteristic sounds that frighten them. When she chooses a host, she puts a single egg on each hair;
- The esophageal female has a different strategy, she sneaks up on the victim unnoticed, making small flights or crawling, then quickly lays 5-20 eggs on a hair.
The number of eggs in the abdomen of a female can reach 700 pieces, each of which later hatches a larva, which will gnaw its prey. Due to such a high fertility, insects reproduce perfectly even with a minimum number of adults and their short life. They have few enemies: among those who eat gadflies and other flies. and bugs - only birds.
The period of flight and mating of gadfly occur depending on the climatic zone of habitat: in the southern regions it is longer, in the northern regions it is shorter.