Life Cycle

Adapted from: The Canadian Pediatric Society, 2004

Lice can live approximately 40-50 days and have a 3 stage life cycle. The three stages are: nit, nymph, and adult.1

NITS are eggs laid by female lice. They are hard to see and are often confused for dandruff or hair spray droplets. Nits are cemented at the base of the hair shaft near the scalp. The eggs develop and hatch approximately 7-10 days later.

NYMPHS are formed once the louse hatches. They are barely visible to the naked eye. The nymph looks like an adult louse but is smaller and cannot reproduce because it is not fully developed. After 12 days, the nymph develops into an adult. The nymph stage typically lasts from Day 11 to Day 22, but can last longer in cold weather.

ADULT lice can lay 4-10 eggs a day (50-150 eggs in their lifetime), starting another generation of lice. The adult stage lasts about 28 days (Day 23 to Day 50).


  1. Resultz Patient Insert: Health Canada Approved (2012).