These aren't a pest problem, but a medical problem. The head louse is a blood-sucking parasite about 3mm long that adapts to the hair colour of its host. The tiny, pearly eggs or “nits” are cemented to the hair close to the scalp, and there are three nymphal stages. The eggs hatch in about eight days and the complete life cycle takes about 18 days.
Transmission is from head to head contact only. The bites cause inflammation and itching, which leads to affected children scratching the scalp, introducing secondary infections such as impetigo or eczema, or literally feeling lousy.
How to get rid of head lice
There are effective insecticidal pharmaceutical lotions and shampoos available in reputable pharmacies and shops. If you have a persistent problem, then you may want to consider seeing your doctor.