They feed on organic materials and the blood-containing excrement of grown fleas. The larvae are found in floor areas, for instance on carpets, under skirting boards and in cracks. They take about 7 to 18 days to develop. A generation of fleas lives for about four to six weeks. The cat flea is most widespread, and it can temporarily transfer to humans.
Fleas often bite several times in direct succession, until their appetite is satisfied.
The itching stops after one to two days, but may then suddenly recur. Sometimes weals form. Fleas can also transmit tapeworms and cause allergies.