How do human lice breed?

Lice are one of the most prolific insects. Throughout its reproductive period, one female can give birth to several hundred parasites, which in turn will also leave offspring. Moreover, the full life cycle of insects is only a couple of weeks. This means that in a month the number of colonies will increase several times, thereby exacerbating the manifestations of head lice and increasing the risk of further spread of the disease.

Let's take a closer look at how lice breed, as well as the features of their structure and development.

Structural features of females and males

Lice belong to dioecious insects. This means that they have both females and males. Distinguishing them from each other is quite simple according to the following criteria:

• body size;
• appearance;
• internal structure.

Body size is one of the main signs by which you can determine the sex of lice. Males of all varieties of these insects are noticeably smaller than females. For example, the body length of a male head louse is 2-3 mm, while females often reach 4 mm. In the wardrobe, males 2.5-3.7 mm, females up to 4.7 mm. Pubic lice - 1 mm and 1.5 mm, respectively.

You can distinguish between male and female individuals in appearance. The end of the abdomen of the first is rounded, while in the second it is bifurcated. The male on the front pair of legs also has a distinct claw-like outgrowth designed to hold the female during mating. She doesn’t have such a device, but there is a spur on her hind limb. Often, in the female, one can also notice spherical interspersed translucent through the wall of the abdomen - eggs. The male is equipped with a copulative organ, which is visible through his body as an elongated object of a triangular shape.

Distinctive features of the internal structure can only be seen under the microscope. The female has a complete set of female genital organs, and the male - male. Through them, the actual reproduction of lice occurs.

Female reproductive system:

• paired ovaries;
• oviducts;
• uterine bag;
• seed receiver;
• vagina.

Male genitals:

• a pair of testes;
• vas deferens;
• adnexal glands;
• a copulative organ whose ejaculatory canal extends to the upper part of the last abdominal segment.

Interesting fact! Among the descendants of the head and body lice hermaphrodites are often found - individuals having a set of both male and female genital organs.

Propagation Features

How do lice breed? This happens according to the usual scenario for all dioecious organisms - mating, fertilization, maturation of eggs and their laying. However, lice still have some distinctive features that have developed during a long evolution.

Mating and fertilization

The reproduction of lice in humans begins with the mating of insects, the purpose of which is the fertilization of eggs. This process has the following distinctive features:

1. Lice become capable of procreation already in the first day after the larval stage.It is marked by the last, final molting, after which the females can immediately begin mating, and their gentlemen are forced to wait several hours.
2. In duration, the entire process can take from 20 to 70 minutes, during which the female gets the seed material of the male, which is then stored in her abdomen.
3. Seed is consumed unevenly, as necessary, throughout the life of the female.
4. Fertilization and the formation of eggs occurs as they move along the oviduct. By the time they exit into the uterine sac, they all already have a dense protective shell that can protect the embryo for the entire period of its development.
5. Egg formation is very fast. From mating to their full maturity, only a few hours pass. Moreover, the more well-fed the female, the faster this happens and the sooner she begins to lay eggs.

Fully formed eggs are called nits. They are covered with a thick layer of the protective shell and are ready to withstand most adverse environmental conditions.

Interesting fact! Only a well-fed louse can lay eggs. A hungry insect stops procreation and hibernates.

Egg laying

After the final maturation of the eggs, the female begins to lay them. Before this, she begins to actively move, choosing the most suitable place. For each species, it is different. A body louse lays eggs in linen. The most typical for her are the following items of clothing:

• lapels on a shirt and trousers;
• inside pockets;
• hem;
• various folds of clothing;
• seams and lining.

At the same time, the female tries to lay her eggs as close as possible to the human body, since heat is necessary for the development of embryos.

How do lice breed on the head? The process of laying eggs in this species is as follows:

1. The female climbs her hair, clinging to the claws specially adapted for this purpose, located at the ends of her legs.
2. Straining the abdominal wall, it squeezes a drop of sticky secretion from itself and moves higher.
3. An egg emerges from the back of the abdomen, which adheres to the prepared substrate.
4. The substance with which the nits attach to the hair hardens and turns into a reliable and very strong shell.

Likewise, they lay their eggs and pubic louse, only she chooses completely different places for this. For her, the most characteristic are the following parts of the human body:

• intimate area;
• axillary hollows;
• eyelashes;
• chest and abdomen in men;
• beard and mustache.

The number of eggs laid by the female depends on the species to which she belongs. So, for example, the head louse lays on average 2-4 pieces. in a day. Lapel - 1-3 pcs. The body louse is particularly fertile. It is capable of producing up to 10 nits per day. If we take into account that the head louse has a breeding period of about 30-40 days, then it is easy to calculate that in its life it will be able to postpone from 60 to 160 nits. A carpenter or pubic louse during the same time will produce only 50 pcs. eggs, and the louse will leave behind more than three hundred descendants.

Interesting fact! Lice have very tender feelings for their owners. An insect removed from human hair, even with a large selection, prefers to return "home".

Developmental stages

Lice are insects with an incomplete transformation cycle. It includes the following stages of development:

• egg
• nymph
• imago.

The egg is the first stage in the development of lice. It can last from 5 days to several weeks, depending on the type and temperature of the environment. The higher the thermometer, the faster the larva will hatch. At a temperature below +22 ⁰With the development of the embryo in the egg is suspended.

The nymph is the larval stage. It includes 3 molts. The developmental period of the larva of the first age is 3-5 days, the second 5 days, the third 4 days on average.

The imago, or adult insect, is a reproductive stage of development. Under optimal conditions, it lasts about a month. During this time, females lay several eggs each day.

How quickly do lice breed? The development cycle of these insects, from an egg to a mature individual, under favorable conditions is 2-3 weeks. Over the course of her life, lasting a little over a month, one female manages to lay a couple of three hundred eggs, of which by the end of the second week, larvae begin to hatch. They, in turn, become capable of breeding also after 2 weeks. Thus, the number of parasite colonies will increase by several dozens, or even hundreds of times, in just 1.5-2 months!

Factors Contributing to the Reproduction and Distribution of Lice

Pediculosis can be called a disease of all time. Even in our time, it is quite common. Children are especially prone to this misfortune. It is enough for at least one child in the children’s team to get sick, as everyone else picks up the infection. And, oddly enough, insects prefer heads that are often washed with shampoo. It turns out on clean skin it is easier for them to feed! However, frequent shampooing is not the only reason for the reproduction and spread of lice. The following factors also contribute to this:

• favorable temperature conditions - about +30 ⁰FROM;
• crowding of people in a limited space;
• sharing of combs, hair pins, towels, hats;
• swimming in ponds, pools and other public places without a protective cap.

The rapid reproduction of insects is also greatly facilitated by the degree of overhang. In people who do not take any measures to eliminate parasites, they begin to multiply with accelerated speed. The thing is that females and males do not have to waste time searching for each other, and they spend it on the sole purpose of their life - procreation.

Unique footage of the birth of lice larvae can be seen in this video: