The louse reaches full maturity at around 10 days after hatching. If mating occurs the female louse can lay 50-100 eggs at a rate of six per day. In most infestations there are usually only a dozen or so lice at any one time, but there can be hundreds of eggs. Clinical Features Head lice usually cause an itch and irritation in the scalp. This can take several weeks to develop after the initial infestation.
Scratching can cause crusting and scaling on the scalp.
Occasionally secondary bacterial infection of the scalp results in small sores on the scalp with tender glands in the neck. Dermatitis can also occur with a heavy infestation of lice. Fortunately head lice are not known to carry any diseases which can affect humans. Lice are around 3mm in length and can be seen moving from hair to hair. Unhatched eggs have a dark area within the shell while hatched eggs are transparent.