image of a flea -- a Cat Flea
Fleas (Cat Flea shown here)

Fleas are wingless insects possessing mouthparts that are adapted for piercing skin and sucking the blood of mammals and birds, causing them to be labeled as external parasites.  Pets and other animals are usually blamed for carrying fleas, and perhaps correctly so.  But rats and mice can also be sources of fleas or causes of continuing infestation.  However, fleas can even survive in homes where there are only humans present, and they can survive a long time without a blood meal, making it a challenge to get rid of them (read the management section of our Fleas fact sheet for control ideas).

Some humans are resistant to or immune to flea bites.  They can live with the fleas and not even be aware of them.  But most people are very sensitive to flea bites.  Flea bites are most likely to be found on the legs, feet and ankles of people in flea-infested areas.  The bites have a red halo around a small red spot, and they may swell.  Several over-the-counter medications may give some relief for flea bites.

Bites from Cat Fleas on a child's feet and legs
Cat Flea bites on a child’s feet and legs

Additional Information:

  • Fleas (UMaine Cooperative Extension)
  • Cat Fleas (Penn State) Cat fleas are the most common fleas on cats as well as dogs. They also infest raccoons, opossums and coyotes.