Household pest
Flea
Ctenocephalides felis (cat flea — the usual indoor species in North America)
A tiny (1.5–3 mm), wingless, laterally flattened insect that jumps and feeds on the blood of pets and people. Flea bites cluster on the lower legs and ankles in humans and around the base of the tail in pets.
Visible identification features
- Very small: 1.5–3 mm, about the width of a sesame seed or less
- Dark reddish-brown to black, laterally flattened (thin side-to-side)
- Powerful hind legs — jumps several inches, unlike bed bugs which only crawl
- Hard, smooth body that is difficult to crush between fingers
- Often found on pets, in pet bedding, and on floors where pets rest
Why it may be in your home
The cat flea is the species found on most dogs and cats in North America. Adults live on the animal; eggs fall into carpets, bedding, and floor cracks, where larvae develop on organic debris. Sightings on people usually mean the pet or its resting areas are infested.
Lookalikes
- Bed bug
Bed bugs are flatter top-to-bottom, cannot jump, hide in mattress seams, and bite exposed skin at night; fleas jump and bite mostly ankles and lower legs.
- Carpet beetle
Carpet beetles are rounded or bristly, do not bite or jump, and are found near wool and lint rather than on pets.
Confused with something else?
Next steps
- Treat the pet and the premises together: a veterinarian-approved product on the animal plus washing pet bedding and vacuuming carpets and upholstery.
- Vacuum frequently and discard the bag or canister contents outside; vacuuming also opens carpet nap so treatments reach larvae.
- Wash or replace pet bedding; treat pet resting areas, kennels, and car interiors.
- Expect a multi-week timeline: pupae can hatch after initial treatment, so repeat per the product label.
Sources
Updated 2026-09-03. Claims are limited to these sources.