Head Lice 101

Pediculosis and Head Lice

How Can I Remove Head Lice?

Head Lice Pictures

Pediculosis (head lice infestations) has been common among humans for hundreds of years. The first documented case of head lice dates back to prehistory. Over the last 30 years, the number of head lice cases has risen increasingly, making the diagnosis and treatment of pediculosis one of the most common responsibilities in general medical practice.

Head lice (P humanus) are found in almost all countries and climates around the world. They are classified as insects or sucking lice. They feed on blood for nourishment. Humans are the hosts for these wingless insects. Lice have 3 pairs of legs, each ending with a claw-like talus that is specially adapted for grasping the texture and shape of a hair strand. Head lice have small frontal mouthparts with 6 tiny hooks that help foster their attachment to human skin during feeding. When the lice are not feeding, the sucking mouthparts retract back into the head. Head lice feed approximately 5 times in a 24-hour period for 35-45 minutes at each feeding. The female louse cannot survive for more than 1 day without feeding off the human head.
The average length of an adult louse is 1-2 mm while the female louse is slightly larger in size than the male. They range from white to gray in color. See our pictures of head lice for easier identification. Head lice can turn a slightly brownish rust color immediately after feeding.

Head lice life cycle
The life cycle of head lice lasts about 30-35 days from egg (or nit ) to adult. The female louse can lay as many as 10 eggs per day, usually at night. She lays them close to the scalp at the base of the hairline and seems to prefer areas close to the nape of the neck and behind the ears for warmth during incubation. When laying the eggs, the female louse secretes an insoluble, cement-like substance to attach the nit to the hair. The incubation of the egg usually lasts between 8 to 10 days. After the nit hatches, the second stage of the life cycle, or the nymph stage, also takes about 8-10 days. The nymph typically molts 3 times before reaching its adult form.