Better than its reputation
The head louse, like all lice, are flattened from the top, unlike fleas that are flattened from the sides. Lice and fleas belong to the subclass winged insects but have secondarily lost their wings.
Appearance and characteristics
The head louse and the body louse belong to the same species but different subspeciesand have been named after where they are found on humans. The two subspecies wereseparated 30,000 - 110,000 years ago when humans began to wear more covering clothing.
Head lice live in the scalp where they suck blood. They cling with their claw-like protrusions of the legs, which are adapted to the diameter of the human hairs.
They can neither fly nor jump so they are spread through head contact between people. The eggs are light in colour, about 1 mm large and are called gnats. The head louse female paste 5-10 eggs per day on the hairs near the scalp. They are stuck really tightly so the lice are usually not spread with help of the eggs.
The adult female lives up to 3 weeks and has the capacity to produce about 200 eggs during her lifetime. From the egg, a nymph crawls, which for about 10 days, undergoes three skin moults before it becomes an adult head louse. The only visible differences between the different nymph stages and the adult, other than size, is the relative length of the abdomen, which increases with each moult. Like the adult individuals, the nymphs are entirely dependent on the availability of human blood and cannot survive long without their human host.