Flea life cycle consists of four stages: egg, larva, pupa and adult form. Adult females lay eggs in batches of 20 pieces. They are folded on the host, but typically quickly fall out of it on the floor. The eggs are very small, oval shaped and gray or white. Eggs change into larvae, which feed primarily biological waste such as wastes, dead insects or vegetable substances. During one-two weeks the larvae produce cocoons and transform into pupae, which are present in cocoons over the next one-two weeks. Then pupae are formed adult forms which must immediately find a host, the source of the blood. Fleas tend to special specific hosts. Fleas, which can be found on the dog, usually do not dwell on humans, but can always be exceptions.