How long do lice live without humans?

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Lice are insects whose life activity is inextricably linked with humans. They never live outside his body and do not feed on the blood of other animals. In extremely rare cases, lice can temporarily settle in the hair of monkeys, but such conditions are far from comfortable for them, which often leads to their sudden disappearance.

Specifics of nutrition and dependence of lice on humans

All types of lice and their subspecies are ideally adapted to their natural habitat. Their size, the shape of the body, the contours of the abdomen and even the structure of the legs contribute to comfortable living on the human body. They differ only in their preferences for certain parts of the body. For example, body lice prefer the folds of clothing, and pubic lice most often live in the groin area, sometimes inhabiting the armpits, eyebrows and eyelashes, especially in children.

Head lice in men can temporarily settle on the beard or mustache, but due to short hair, this is not convenient for them, which often leads to their sudden disappearance. Regarding their life expectancy, it is extremely short. Each adult can live on humans for up to 46 days. To this indicator should be added 2-2,5 weeks, which the nymph development stage takes. Pubic lice live a little longer - up to 3 months under favorable conditions.

Life cycle of a louse

In addition, the classification of lice, which is initially associated only with humans, does not allow them to migrate to pets, and vice versa. All types of lice are vitally dependent on humans, and only body lice can remain on clothing or the inside of linen for a short time, but then they require blood and return to the skin of their owners.

However, how long can lice live without humans? This issue remained controversial for a long time. Some scientists argued that these insects can starve for a long time, only by suspending their reproductive function. However, as a result of long-term experiments and a detailed study of the behavior of lice, it was found that one adult individual is not able to fast for more than 2 days, sometimes up to 10 days, with a strong drop in temperature to 10-12 °C.

In any case, starvation for lice means quick death. For example, bed bugs can go hungry for several months, and ticks can go hungry for several years.

Why do lice live on humans?

During their existence, all types of head lice managed to undergo evolution and adapt to life on humans as much as possible. The structure of their legs has also undergone changes. Currently, they have special hooks that allow insects to cling to hair. The oral apparatus is adapted only for the absorption of blood, while the digestion of solid food is impossible.

Reproduction occurs with the help of humans. The female moves along the hair and lays an egg on it, which is subsequently secured with a special adhesive substance. Nits located near the hair roots fall onto the skin immediately after hatching and begin to feed on blood.

As for body lice, which live on human clothing, they have a slightly different structure of their legs. They cannot move on hair, but they move easily on most textiles. Here they spend their free time, mate and lay eggs, crawling onto the body only when necessary. The bites of this type of lice spread throughout the body, even covering the lumbar region. They can die if a contaminated item of clothing is left unattended for several days.

How and how long lice live on humans

The life cycle of a louse is usually about 40 days and includes three stages: the egg or nit, the larva, which goes through three moults, and the adult. The first two stages take up to 15 days. The larva already feeds on blood, but is able to reproduce only at the adult stage. A female louse can lay up to 4 eggs per day, which contributes to a rapid increase in the population.

There are three types of lice in humans: head louse, body louse and pubic louse. The head louse lives on the scalp, the body louse prefers to hide in bedding, clothing and other textiles, and the pubic louse is found on the genital hair, around the anus and in the armpits.

Pubic lice differ from head lice in the width of their legs - those of pubic lice have a triangular cross-section, which allows them to move better in the groin area, while head lice have legs adapted for moving through hair with a round cross-section. Body lice, despite their habitat, always remain close to the human body, as they need frequent feeding - up to 6 times a day.

Can lice live on people other than humans?

Yes, lice can be temporarily outside the human body, but this is not their normal state. They are able to move on various surfaces and even withstand slight pressure, such as sand or pebbles on the beach. Lice can crawl up to 50 cm or even more. Although they cannot fly, they crawl quite quickly, which explains the high risk of infection even without direct contact with an infected person or his things. Even at a distance of half a meter from an infected person or his things, lice can reach a new victim. And even if there are no visible dangers, lice may be nearby, so there is no guaranteed way to avoid getting lice.

However, being outside a person's head or genitals is temporary. Lice strive to get to a food source, and without food they can live no more than 4 days under ideal conditions, although more often this critical time is 2 days.

The optimal temperature for lice to live is 30-36 degrees, which makes the human body an ideal environment for them. Lice also tolerate air temperatures above 23 degrees. However, when the temperature drops below 10 degrees, lice can survive no more than 24 hours, and in case of frost they die within a few hours. They also do not survive at air temperatures above 39 degrees.

Can nits survive without humans?

Lice eggs are called nits. During her life, a female can lay up to 120 such eggs. Nits are small, round, white in color and are attached to the base of the hair with an adhesive substance. Inside them, the larva develops within a week. The nit shell is quite strong, protecting the larva from mechanical and partly from chemical influences. Under unfavorable conditions, nits, or rather the larvae in them, can fall into a state of suspended animation, which is a kind of deep sleep with the suspension of all organic functions. In this state, the larva stops its development, but remains alive. Some nits can remain in a state of suspended animation for up to two weeks. When returning to normal conditions, they continue their development, turning first into adults and then into adult lice.

Do lice live in water?

Lice infestations are common in swimming pools, spas, saunas and beaches. Parasites are able to survive even in water, where they can stay for up to two days. Staying in water has no effect on their development. After joining a new victim, they retain the ability to feed and reproduce.

Why Lice Are So Hard To Kill


During their lives, lice periodically leave their normal habitat, moving across various surfaces to find new prey. At optimal air temperatures, they can survive up to 4 days without food. Nits can also enter a state of suspended animation and remain in it for up to 2 weeks, although most often they die without access to food earlier.

It is important to remember that maintaining personal hygiene does not guarantee protection against lice infection, since they can move quite freely and be in different places. When using lice products, you should be careful not to spread the lice to other surfaces.

It is also important to treat not only the hairy parts of the body when treating head lice, but also places where lice may temporarily hide. Guaranteed destruction of parasites is possible with thorough treatment of all surfaces on which they may be located, for example, bed linen, blankets and mattresses.

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