It only takes takes only one Louse to start an infestation. Once the louse is on your head it will lay approximately 8 – 10 Nits (eggs) a day. The eggs glue themselves to a hair strand. The glue is what makes it hard to pull them out. It takes about a week for the egg to hatch. It can only hatch if it is still attach to the strand of hair. Once all the eggs have hatched, the head is full of nymphs ( baby lice). In about 8-10 days or so, the nymphs become adult lice. Then about 10 lice are laying 8 to 10 eggs daily. And now you see how quickly a small problem becomes a bigger problem.
Your child may not start itching for a couple of weeks and when they do there are approximately 10 adult lice, and each day 6 to 10 eggs are hatching.
Lice Ranger recommends combing at least once a week. It won't prevent your child from getting lice but it can prevent it becomming a big problem.