Young parasites are commonly referred to as 'nits, ' which is a four-letter word. Nits are the eggs of lice, which are small, wingless insects that feed on human blood. They are most commonly found on the scalp and hair of young children, but can also be found on adults. Nits are usually white or yellow in color and are very difficult to remove. They can cause itching and irritation, and if left untreated, can lead to more serious health problems.