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The head louse is the most common parasite. It is a small greyish-brown insect about 2-4 mm long and that generally lives and nests on the scalp, feeding on blood obtained from its host by biting the head.
These parasites reproduce rapidly. The female louse, after mating, lays about 150-300 oval eggs that are about 0.8 mm long at the root of the hair of the scalp. They are fastened tightly to the hair and can be very difficult to remove.
After six or seven days, the louse hatches, leaving the empty nit behind. Nits are bright white and are found attached to the hair all over the head.
