Some insects, especially blood-sucking ones, are carriers of causative agents of dangerous human and animal diseases.
Insects – pathogens and human parasites
Malaria mosquitoes are carriers of malaria pathogens.
Malaria and common mosquitoes are bloodsuckers, and their larvae developing in water feed on microorganisms and suspended organic debris. The larvae breathe atmospheric air using a respiratory tube.
An anopheles mosquito can be distinguished from an ordinary mosquito by landing: an ordinary mosquito holds its body parallel to the surface on which it sits, and an anopheles mosquito – at an angle.
Their larvae also differ. The larvae of anopheles mosquito, rising to the surface, keep the body parallel to the surface film of water, the larvae of an ordinary mosquito – at an angle to it.
To reduce the number of malaria mosquitoes, marshes are drained, fish are raised that eat mosquito larvae and pupae. An important role in reducing the number of mosquitoes is played by their natural enemies – insectivorous birds (swallows, swifts) and dragonflies.
Lice and fleas are dangerous insect bloodsuckers.
A human louse parasitizes on humans (lice parasitizing on humans is called head lice), causing severe itching in humans. When fed, lice can transmit typhus pathogens to the host. Many types of lice parasitize pets.
A female louse lays up to 300 eggs in her life, sticking them to her hair or threads of clothing. Elongated, oval, whitish-yellow lice eggs are called nits.
Fleas are carriers of plague pathogens. Plague germs enter the body of fleas by sucking the blood of rats, ground squirrels and other rodents with plague, as well as humans.
A bed bug usually attacks a person at night and sucks blood, and spends the day in shelters – in furniture, behind wallpaper. One of the features of bedbugs is the ability to fast for several months. The bug larvae go through five instars (molts), and for the transition to the next age, the larva must necessarily drink blood every time. If this does not happen, then the next molt does not occur.
House flies live in human dwellings, garbage dumps, and farms with pets. They carry eggs of ascaris, the causative agents of typhoid fever, dysentery, cholera.
Autumn flare appears in living quarters from the end of summer and is familiar to many for painful bites. She can carry pathogens of such a dangerous disease as anthrax.
And the African tsetse fly carries a trypanosome, the causative agent of sleeping sickness, which is deadly for humans.
Insects are parasites of pets
Horseflies and gadflies cause great harm to animal husbandry.
Horseflies females suck the blood of animals. When there are a lot of them, then cows, sheep, goats lose much weight, reduce milk yield.
In gadflies, the mouth organs are not developed, and these insects do not feed, but the larvae of many species are parasites of animals and humans. Females of the bovine hypodermic gadfly attach eggs to the wool of the cows, the larvae that appear are introduced into the skin. At the end of their development, the grown larvae cause the formation of purulent nodules with fistulas and fall out of them, and then pupate in the soil.