TC Flea facts from the National Pest Control Association.
There are four stages of fleas: egg, larvae, pupae and adult.
Female adults lay four to eight eggs after each blood meal, laying some 400-500 eggs during their lifetime.
The eggs are deposited on or between an animal's hairs and either fall or are shaken off. They're frequently found in cracks and crevices where pets sleep or frequent. Eggs usually hatch in one to 12 days.
Flea larvae move about, have chewing mouthparts and feed on organic debris but almost all require dried fecal blood (from adult fleas) in order to complete development. The larvae last a few weeks to several months.
The pupae stage can last four days or up to one year. The more favorable the conditions, such as relatively high humidity and moisture, the shorter the larvae and pupae stages.