The only thing that can be hated by people with flies is probably lice. Lice, like flies, can be seen everywhere and are notorious for being harmful to human health. Lice is a parasite that lives on animals and feeds on blood.

There are three kinds of lice parasitic on human body: body lice, head lice and pubic lice, among which body lice are the most common.

Body lice, commonly known as clothing lice, are gray or gray-white, with a slightly olive-shaped head and a long, flat abdomen, which is divided into 9 sections with a pair of stomata on each side. The abdominal end of the male louse is blunt, and the end of the female louse is forked, which looks like a "W" shape.

Head lice are dark black in color, small in size, and dark in abdominal margin, and others are similar to body lice.

The crab is gray-white, almost equal in body width and body length, with short abdomen, inconspicuous segmentation, small front legs and thick middle and rear legs.

They are the main vectors of epidemic macula, cold and tick-borne relapsing fever.