Lice Life Cycle


Everyone goes through an itchy, blood-sucking and skull scratching episode of lice in their hair. It’s prominent in the human scalp as it gets body heat from that area. Lice fall under the order Phthiraptera that includes chewing louse (Amblycera) and sucking louse (Anoplura). Chewing louse resides on birds and some other mammals like cattle. Sucking louse resides on humans with improper hygiene conditions. Sucking louse is known as Pediculus humanus that infests the human head. Louse measures up to 11 mm in length and varies in colours like white, brown, yellow or black.

Let’s look at the life cycle of lice:

1) The Egg – Stage 1 –

Lice eggs are also known as nits, they are very tiny particles that are found on the human scalp. Due to its size, it can be mistaken for dandruff or other dirt particles on the scalp. It measures up to 0.8 mm, oval-shaped and yellow or white coloured. These eggs take around one week to hatch into nymphs.

2) The Nymph – Stage 2 –

The nymphs are tinier versions of lice. Initially, the nymph is yellow to white coloured but undergoes three stages of moulting. With each stage of moulting the nymph transforms to the adult lice. This nymph takes a week to enter the adult stage.

3) The Adult – Stage 3 –

The adult lice have fully-grown and measure up to 2 mm in length. Almost similar to the size of a sesame seed, the adult lice live up to 30 days if fed frequent blood meals on a daily basis. The adult lice will die in one or two days if it’s off the host.


Lice have six claws that they use to crawl up and down the hair and catch hold of hair as well. They are wingless, blood-sucking insects that cause an infestation and can pass on from one head to the other. Due to an increase in the lice infestation, several insecticidal shampoos have been introduced to fight lice. But unfortunately, this ascends in insecticidal shampoos made lice resilient to insecticides. The only way out of this infestation is to maintain proper hygiene habits.

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Frequently Asked Questions on Lice Life Cycle


What are the different types of human lice?

The lice found on the scalp of a human head are called a head louse. The other kinds of human lice are body louse and pubic louse. The pubic louse is also known as ‘crab’ louse because of the shape resembling a crab.


Does head lice infestation cause any diseases?

No, they are not carriers of any diseases and do not cause any diseases. But if the infestation prevails for a long time then it can cause extreme skin irritations.


What does a head louse look like?

The head lice are the size of a sesame seed, has 6 claws, are wingless and is usually yellow, white (nymphs), brown, black (adults) in colour. Due to their miniature appearance, they can be mistaken for dandruff or other dirt particles. Lice usually nest on the surface of the scalp or 6 mm from the root.


What are nits and what do they look like?

Nits are known as lice eggs. They are oval-shaped, pointed on one side and antennae on the other side. They are brown in colour and are attached to strands of hair.

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