Generally speaking, the types of lice are numerous - only in mammals there are more than 500 species of these insects. At the same time, only two different types of lice parasitize on humans - human louse (Pediculus humanus) and pubic louse (Pthirus pubis). They quite easily differ from each other both externally and in their habitats and parasites.
It is often incorrectly considered that there are two types of lice in a person, but three: for example, they also distinguish between head and body lice. However, these are not separate species, but merely forms (scientists call them morphotypes) of human lice, peculiar types of lice. They are adapted to living in different conditions: the head - in the hair of the head, and the wardrobe (underwear) - on the clothes - and during the parasitism on the person they managed to develop such differences in lifestyle that they almost never intersect or intersect on the human body.Laboratory studies have shown that they have not yet reached complete separation of different species, and if they exist together (only possible in artificially created conditions), they are able to interbreed and produce fertile offspring.
The photo below shows the different types of lice in humans - human and pubic:
And in the next photo - varieties of lice in humans. The first is a head louse, the second is a clothes louse:
On a note
No matter how numerous lice are in nature as a whole, their species are specific in that they are adapted to life on only one species of the host animal. So, human lice cannot live on the body of other mammals, with the exception of a few species of monkeys, and dog lice live only on dogs - and so on.
That is, a person can get lice only from another person, but not from animals. In this regard, lice are significantly different from fleas. The latter have similar sizes, but can parasitize on a large number of host animal species.
All types of lice in humans are similar in that the full cycle of their reproduction takes place on the body of the host or in close proximity to it — on hair or clothing.All types of lice that occur in humans feed exclusively on blood, and unlike other parasites, each individual bites the victim several times a day - most blood-sucking insects do food every few days (for example, bed bugs), or even weeks.
Head lice are the most common parasite and are often found even in people living in normal sanitary conditions. This insect infects only the scalp, only in extremely rare cases, moving men to sideburns and beards.
In general, this type of lice differs from the dressing in a slightly darker body color - it is grayish-brown. After feeding, the color of the insect's body becomes darker than it was before, due to a drop of blood in the stomach. The photos below show several insects of this form:
The main difference between head lice and underwear is the difference in their habitats.
Adult Size head lice - about 2-4 mm. Lice larvae have a size of about 0.6-2 mm. The head louse eggs are called nits and firmly attached by the female laying them off to the hairs about 2-3 cm from the surface of the scalp.
Head lice breed constantly, regardless of the season. They feel great at a temperature of 30-33 ° C, and continue to multiply in the temperature range from 23 ° C to 40 ° C. Lice die when the temperature drops below 0 ° C or when it rises above 45 ° C.
This type of lice cannot live without hair on the head. The picture below shows a louse crawling through a bunch of hair:
Accordingly, the most simple and reliable way to bring out the head lice is a haircut "bald." In other cases, you should use shampoos, sprays or creams containing insecticides, or special hard and thick combs from lice and nits.
Cootie (another name - linen louse) looks very similar to the head and has a similar body structure with an elongated abdomen, as well as similar sizes. It differs from the head louse in body color - it is usually white or light gray with a yellowish tinge, and, of course, habitat.
The clothes louse is adapted to life only on clothes permanently or very often located on the human body. She cannot live in her hair or in clothes that a person dresses very rarely.Therefore, tramps, refugees and asocial individuals, who do not change their wardrobe and rarely wash clothes, are most often the victims of body lice.
Below the photo shows this type of lice - visible accumulation of parasites on the fabric:
A body louse bites a person just under clothes and in most cases - on hairless areas of the body.
These parasites lay their eggs (nits) on clothes, and therefore combating them is usually simpler than removing head lice: here you need to either boil or treat the things themselves that are dangerous for lice and wash the body thoroughly. insects.
On a note
All louses withstand sufficiently long immersion under water. When washing the head and hair in the groin area, the lice themselves, clinging to the hair, are not washed off, and moreover, the nits remain intact. Individuals that were trapped on the skin at that moment can only be washed away.
Of all the varieties of lice in humans, the pubic louse is the smallest. The adult individual reaches a length of no more than 2 mm, and the first instar larvae - only about 0.5 mm. Without a microscope, these insects look like small, brownish points of a slightly flat shape.
Pubic lice affect almost exclusively the hairy part of the body in the groin, but in very rare cases they can settle in the armpits, and in some cases (especially when infected by water) - on the eyebrows and eyelashes:
Under the microscope, the difference in the shape of the body of the pubic louse from the human louse (head and dress) is clearly visible - the parasite is much shorter and has more massive legs relative to the body size. In the photo below you can see both types of lice at high magnification:
Pubic lice are transmitted most often through sexual contact, and therefore infection with them is considered a kind of venereal parasitosis. However, in some cases, pubic lice are transmitted on water or when using common clothes.
It is interesting
Experts have noted in recent years a decrease in the infection rate of pubic louse and a reduction in the number of this parasite in general. It is believed that one of the reasons for this is the fashion for shaved pubes, because of which insects are deprived of the only suitable conditions for their existence.
Lice in other animals
In other animals, species of lice are significantly more diverse in size and body shape.
- A hare louse with a hairy and very dense body.It parasitizes several species of hares and rabbits.
- Pig lice, quite large and having a body length of about 5 mm. It settles behind the ears, on the folds of the neck, abdomen and legs of domestic pigs and wild boars.
- Dog louse belonging to the squad of lashing. In addition to the host’s blood, it can also feed on pieces of skin and secretions of the skin glands of an animal.
- An elephant louse that adapts to the owner's lack of hair is that it has a proboscis widening at the end, due to which it sticks tightly on the skin when it bites.
The photo below shows some of these types of lice. All species that live on animals are not dangerous for humans:
In addition to the lice itself, the eaters in animals are also very well known. There are more than 3,000 species of them, and they lead a louse-like lifestyle. Their main difference from true lice is the ability to feed not only with blood, but also with various derivatives of the host's skin. Bird eaters in birds are even more numerous, but they are distinguished from lice by even more features.
Considering what lice are, one can not forget about the famous book louse.
It is not a typical louse, but belongs to the suborder of hay and feeds with various organic residues: from various groceries.products to bookbinding. Directly to humans, it is not dangerous.
Interesting video: details about lice and how to deal with them
Pubic lice under a microscope