Reviewed by William "Willy" Vizcarrondo, NYS DEC Certified Commercial Pesticide Applicator C1825832. Updated September 23, 2026.
Short answer
The fleas came with the house, the furniture or an animal you don't own. UC IPM notes wild animals including feral cats, opossums and squirrels cause outdoor flea problems, used carpets and furniture can bring fleas in, and fleas in cocoons can stay dormant for up to 12 months and emerge when warmth and foot traffic tell them a host is back. Empty houses and new tenants are the classic case.
One of three places. First, a previous animal: a house or apartment where a dog or cat lived carries flea eggs and cocoons in the carpet, the baseboards and the floor cracks after the pet is gone. UC IPM notes fully formed fleas can remain in their cocoons for up to 12 months in cool conditions, and that warmth in the 70 to 90 degree range and mechanical disturbance such as vacuuming or people walking trigger emergence. Move into a vacant house in June and turn on the vibration of daily life, and they hatch. Second, wildlife: a stray cat under the deck, an opossum in the crawlspace or squirrels in the attic, which UC IPM lists among the sources of outdoor flea problems that end up at the door. Third, something you carried in. UC IPM's advice to thoroughly clean items you bring into the building, such as used carpets, is about exactly this.
Because you're the only warm thing in the room. Fleas emerging from cocoons in the carpet jump at the first host that passes, and without a dog or cat that's a person, at ankle height. UC IPM describes the flea bite as a small central red spot surrounded by a red halo that itches. A cluster of those around the ankles and lower legs, worst in rooms with carpet or where an animal used to sleep, is the pattern. Check with a white sock test: walk slowly through the room in white socks and look for dark specks that jump.
Vacuum, treat, and cut off the source. UC IPM notes vacuuming is very effective in killing larvae and that the disturbance also makes cocooned fleas emerge, so daily vacuuming of carpets, upholstery and floor edges, with the bag or canister emptied outside, is the first tool. The second is a treatment with an insect growth regulator, methoprene or pyriproxyfen in UC IPM's list, applied to the carpet and floor cracks so the eggs and larvae can't develop, and UC IPM notes fleas continue to emerge for about two weeks after treatment, so the vacuuming keeps going through that. The third is the source: the stray cat gets kept out from under the deck, the opossum gets excluded from the crawlspace, the attic animal gets removed. Fleas without a host die out; fleas with a wild host under the porch keep coming.
The no-pet flea call is usually a new tenant in a Long Beach or Hempstead apartment, a family that just closed on a house in Levittown or Massapequa that sat empty for a summer, or a homeowner in Huntington or Bay Shore with a feral cat colony next door and a crawlspace they've never looked in. Bobby Bugs treats the floors with a growth regulator, checks under the house and the attic for the animal that's feeding them, and general insect work like fleas is done without a guarantee, so we tell you up front what the two weeks after treatment look like.
Related
For a while. Adults need blood and will bite people, but they don't breed well on people, so a flea population in a house with no animals shrinks over weeks unless there's a wild host nearby. The problem is the cocoons already in the floor, which can keep hatching for months.
Up to a year as pupae in their cocoons, according to UC IPM. They wait for warmth and vibration, and they emerge when someone moves in. That's why a house that sat vacant can have a flea problem the first week.
Fleas if the bites are on the ankles and legs and you see tiny dark insects that jump; bed bugs if the bites are on skin that was exposed in bed, arms, neck, back, in lines or clusters, and you find rust-colored spots on the sheets and mattress seams. Bed bugs don't jump and you won't see them by day.
Still not sure? Call (516) 509-6001 and we'll tell you what you're dealing with.