How Long Do Fleas Live
Fleas can live up to a year and a half when they have a food supply, the optimum temperature (70F to 85F), and ideal humidity (70%). In reality though, most live for an average of 2-3 months.
Even if you remove the pets from your house for a time, the fleas can still survive for several months without feeding.
Most fleas that we encounter because of our pets are cat fleas and dog fleas, which actually can not easily sustain live by feeding on humans. According to laboratory experiments, fleas that fed on humans for a short amount of time were not able to produce viable eggs. The cat fleas were required to feed on human blood for a long time (12 consecutive hours) to produce viable eggs. By comparison, a cat flea can produce viable eggs after feeding on a cat for a much shorter period of time. So while fleas often bite humans, the ones most commonly encountered cannot realistically sustain on humans.
Flea eggs can live in your carpet in a dormant state for up to a year depending on the environment. This is why it is important to vacuum frequently. Vacuuming can get rid of 30-60% of the fleas from carpeting.