How Do Fleas Reproduce?

The way fleas reproduce depends on their species and environmental conditions, states "Flea Control: How to Get Rid of Fleas Naturally." For example, the water flea reproduces asexually under normal conditions. These fleas only produce females until abnormal conditions, such as overcrowding or a limited food supply, cause them to asexually produce only males. The male fleas then mate with the females to continue reproduction until conditions change again.