If you're a pet parent, you've probably wondered, "What do fleas look like?" at least once – especially if you've noticed your pet scratching a little more than usual. One of the few downsides of having a pet is that they're very susceptible to carrying these pesky parasites, which is why it's important to invest in the best topical flea treatment for cats or best flea treatment for dogs.
Fleas are sneaky little creatures, and because they move so quickly, many owners find them tricky to spot – and the longer you leave them, the more will appear on your pet and around your home.
Below, expert vet Dr Rebecca MacMillan has compiled a complete guide on fleas: from what they look like and the signs to watch for, to her top tips for prevention and treatment.
What do fleas look like? Are they visible to the human eye?
Fleas are small, flat, oval-shaped insects with hard shells covered in hairs. They are dark or reddish-brown in color and measure around 1.5–3mm long. It may be hard to see them, especially if your pet’s hair is a similar color.
They are visible to the human eye, but a magnifying glass can be used if you need to take a closer look. These creatures have six legs: four short ones and two longer ones that they use to jump from place to place as they are wingless and cannot fly.
Dr MacMillan says: "The main reason why people don’t spot them is because they are fast-moving. When you part your pet’s fur, they may be seen briefly before running for cover."
What do fleas and flea eggs look like on pets?
When checking your pet for fleas you should look out for adult fleas, flea dust, eggs, or larvae. Adult fleas are small brown insects that can be found crawling through your pet’s fur or attached to their skin. If you can’t see the insect itself, you may spot flea dust or flea feces, which looks like grains of blackish-red pepper.
Flea eggs are tiny, oval, white specks (around 0.5mm), which could be mistaken for dandruff or salt grains and flea larvae resemble tiny white worms. Both of these are difficult to see with the eye so it is more likely that you’ll spot the insects or flea dust on your pet.
Dr MacMillan says: "Many owners mistake them for pieces of dander or dandruff, if they spot them at all. Flea eggs are designed to roll off your pet and into the environment, so you won’t find all that many on your pet anyway."
What are the signs of fleas on your pet? How do you tell if it is a flea?
If you’re wondering whether your pet has fleas, there are a few things Dr MacMillan suggests looking out for.
1. Seeing specks of black-brown flea feces in your pet’s coat
"You may spot this just by looking, or by running a fine comb through their fur. If you can’t tell whether it is flea poo or general garden dirt, then smudge the specks onto some damp cotton wool. Flea feces contain digested blood, so they will make a red-tinted smudge, whereas garden dirt won’t (or will only smudge brown)."
2. Increased itchiness and hair loss
"In my experience, many pets with fleas are especially itchy on their lower backs and rumps. Your pet may also have scabs or sores on their skin, particularly if they have a sensitivity to flea saliva."
3. Seeing the fleas themselves
"This can be more notable on hairless areas of the body, like your pet’s stomach or groin area. But parting the fur on other areas of the body may reveal a flea or two."
Where do fleas come from?
Your pet is most likely to get fleas from being outside, although they can originate in the home too. They can either be found living in the environment on long grass or bushes or attached to an animal host, which they feed off before mating. Flea eggs hatch in shady conditions.
Once they are fully grown adults, fleas can jump from one animal to another. Your pet may pick up fleas from a bush or from another animal – this could be another cat or dog, or even a squirrel or raccoon. It’s important to understand how cats get fleas and what places your dog may pick up unwanted critters so you can try to prevent it from happening.
How do you know if your house has fleas?
If you want to know if your house has fleas, the first thing to do is check your pet. Are they showing signs of a flea infestation such as scratching? Do they have bites? If you can’t see any, run a paper towel over their fur and if red streaks of blood show up, it’s a sign of fleas.
You can also check your home. Look closely at your carpets, curtains, and furniture for the tiny jumpers. If they aren't visible to the eye, put on a pair of knee-high white socks and walk around on your carpet for a while, then put your feet up on the furniture. The pesky critters will probably attach themselves to the fibers on your socks.
Can fleas crawl on or bite humans and pets?
Fleas do bite humans as they feed on blood, but they don’t tend to live on humans as hosts, as we do not have enough hair for them to attach themselves to. Instead, they prefer to attach themselves to animal fur.
Flea bites on a human will generally be scattered around our legs or feet. They are small red bumps with a faint red ring around them. On our pets, flea bites are raised red or pink spots, again, often surrounded by a faint red ring.
How to treat fleas on pets
Follow these simple tips to get rid of these tiny parasites:
- Bathe your pet in lukewarm water with a vet-recommended flea shampoo. You may need to look into how to give a cat that hates water a flea bath.
- If your pet is not a fan of baths or water, try using a flea spray.
- Dry your pet with a towel and using a flea comb brush through their fur to remove the fleas. Rinse the comb in warm soapy water after each brush to kill the fleas.
- Flea collars, tablets and steroid creams can also be used to treat fleas, but make sure you check with your vet first.
- Check your pet regularly for fleas to prevent future infestations and to get rid of the problem early on.
How to get rid of fleas around the home
If you want to know how to get rid of fleas, there are a number of things you can try:
- Regularly clean your pet’s bedding with hot water and soap to kill any fleas.
- Wash your pet with a vet-recommended flea shampoo to ward off these pesky critters.
- Use a powerful vacuum to make sure your carpet picks up any unwanted parasites. Empty the vacuum and take the bins outside.
- To be extra sure you kill off fleas, use a steam cleaner on your carpets, furniture, and upholstery.
- Use an IGR (insect growth regulator) flea spray, which prevents eggs from hatching into fleas.
- Mix one part baking soda and one part salt, sprinkle it over your carpets, and vacuum. This should dehydrate flea larvae and get rid of them.
- Leave bowls of soapy water out around the house underneath lights. Fleas will be attracted to the light and land in the soapy water, which will kill them.
How to prevent fleas
There are a number of ways to prevent fleas in the first place, including knowing the best flea medication for your dog or cat.
- Bathe, brush and check your pet regularly for fleas.
- Keep your house clean using a powerful vacuum or steam cleaner.
- Regularly wash your pet’s bedding.
- Limit the amount of time your pet spends outdoors.
- As well as preventative medicine, you could also try researching the best flea collar for your cat or dog.
Read next: How to get rid of fleas in your home and on your pet and what kills dog fleas instantly
Rebecca is a veterinary surgeon who graduated in 2009 from the Royal Veterinary College in London. She has a wealth of experience in first opinion small animal practice, having done a mixture of day-to-day routine work, on-call emergency duties and managerial roles over the years. She enjoys medicine in particular and she is proud to have recently achieved a BSAVA postgraduate certificate in small animal medicine (with commendation). She writes on various feline and canine topics, including behavior, nutrition, and health. Outside of work and writing she enjoys walking her own dog, spending time with her young family and baking!
Edited by Georgia Guerin.
This page was last updated in August 2025 by Megan Milstead.
