More about this in the control section. The eggs hatch into a larval stage. Larvae are very small, white and mostly translucent. They look like tiny worms with sparse hairs on the body. At 80 degrees F, it takes 3 to 4 weeks for fleas to develop from egg to adult.
Moisture also plays an important role in larval development.
There is sufficient humidity within the home to complete development. Outdoors is a different matter. In dry weather fleas may only survive in cool, damp areas. Larvae feed mainly on undigested blood voided by adult fleas. The blood dries on the hair and falls from the animal.