The Pet Tells You First
A cat or dog with fleas usually scratches more, but the change is often subtler than frantic scratching. Watch for short, sudden bouts of nibbling at the base of the tail, the back of the neck or the belly, a cat that has started over-grooming one area until the fur thins, or a dog that gets up from its bed, turns round and lies down again more than it used to.
None of that proves fleas on its own. Skin conditions, allergies and other parasites can all look similar, so a vet is the right person to examine the animal. What the behaviour does is tell you where to look next.
Flea Dirt and the Wet Paper Test
Flea dirt is the droppings of adult fleas, which are mostly digested blood. It looks like fine black specks, a bit like ground pepper, and collects in the animal’s coat close to the skin, in its bedding, and on the sofa cushion it favours.
To check, run a fine comb through the fur over a sheet of white kitchen paper, or shake the pet bedding over it. Dampen the specks with a few drops of water and wait a moment. Ordinary dirt stays black or grey. Flea dirt spreads out into red-brown smudges as the dried blood dissolves.
This is the test that settles it. Red-brown smudges on damp white paper mean fleas have been feeding on your animal, even if you have not yet seen a single live one.
The White Sock Test
Put on a pair of plain white socks, pulled up over the ankle, and walk slowly around the rooms the pet uses most. Shuffle a little on the rugs and along the edges of the carpet, and linger by the sofa and the pet’s bed. Then look down.
Newly hatched fleas jump towards movement and warmth, and against white cotton they show up clearly as small dark dots that move. A few minutes of this in the evening, when the house has been quiet, often tells you more than a day of searching.
Jumping Specks and Bites
On pale floors, bathroom tiles or a light-coloured duvet you may see a dark speck that is there one moment and gone the next. Fleas do not fly; they jump, and the jump is so quick it looks as though the speck has vanished.
Bites on people are the other sign, and often the one that prompts the call. Flea bites tend to be small, itchy red spots, frequently in clusters around the ankles and lower legs, because that is as high as a flea on the floor usually reaches. They bite people but do not live on them.
If you are not sure fleas are the culprit, our guide to telling flea bites from other bites covers that, and the bed bugs vs fleas comparison deals with the one people most often confuse. For itching, soreness or a reaction, speak to a pharmacist or your GP.
When You Have Found Them
One positive sign is enough to act on. A flea you can see is the adult stage, and behind it are eggs, larvae and cocoons in the home that no test will show you. Where those stages collect is mapped out on our page about where flea larvae live in a house.
Book the pet in with the vet, and if the signs are in more than one room, ring 0118 336 1366 to talk about treating the home.