Lice Life Cycle


Everyone goes through an itchy, blood sucking and skull scratching episode of lice in their hair. It’s prominent in human scalp as it gets body heat from that area. Lice falls under the order Phthiraptera that includes chewing louse (Amblycera) and sucking louse (Anoplura). Chewing louse resides on birds and some other mammals like cattles. 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 colors like white, brown, yellow or black.

Let’s look at the life cycle of a lice:

1) The Egg – Stage 1 –

Lice eggs also known as nits are very tiny particles that are found on 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 colored. 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 colored but undergoes three stages of molting. With each stage of molting the nymph looks like the adult lice. This nymph takes a week to enter the adult stage.

3) The Adult – Stage 3 –

The adult lice have full grown parts like 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 increase in the lice infestation, several insecticidal shampoos have been introduced to fight lice. But unfortunately, this ascend in insecticidal shampoos made lice resilient to insecticides. Only way out of this infestation is to maintain proper hygiene habits.

To explore more information about lice and other insects, register by BYJU’S Biology.

Frequently Asked Questions on Lice Life Cycle

What are the different types of human lices?

The lices found on the scalp of a human head are called head louse. The other kinds of human lice are body louse and pubic louse. Public 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 lice look like?

The head lice is the size of a sesame seed, has 6 claws, are wingless and is usually yellow, white (nymphs), brown, black (adults) in color. 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, pointy on one side and antennae on the other side. They are brown in color and are attached to strands of your hair.

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