You can do this by measuring how far the eggs are positioned from the scalp. Eggs are laid near the scalp. Hair grows at about one centimetre a month. Therefore an egg that is situated 2 cm from the scalp was laid about 2 months ago.

You can do this by measuring how far the eggs are positioned from the scalp. Eggs are laid near the scalp. Hair grows at about one centimetre a month. Therefore an egg that is situated 2 cm from the scalp was laid about 2 months ago.