Bed bugs vs fleas: how to tell what is biting you

If you wake up with itchy marks on your arms, neck or face and your pets are not scratching, suspect bed bugs. If the bites are around your ankles and lower legs, or a cat or dog in the house is scratching more than usual, suspect fleas.

That first guess is useful, but it is only a guess. Everyone reacts differently. The BPCA notes that some people show no reaction to a bed bug bite at all, so two people in one bed can have very different mornings. Mosquitoes, mites and skin conditions can look similar too.

So treat the bites as a clue and the insect as the proof. The two pests live in different places and need different treatment, which is why it is worth ten minutes with a torch before you spend money on sprays. The table below shows the differences side by side.

The NHS describes bedbug bites as raised and itchy, often in a line or grouped together, and usually on skin left exposed in bed. It notes that they tend to look red or pink on white skin, and brown, red or purple on black or brown skin, where they can be harder to see.

Flea bites are lower down. The NHS says they are usually found in groups below the knees, and Lambeth Council draws the same line: bed bug bites spread across the body, flea bites stay below the knee. Adur & Worthing Councils add one useful exception. Children who sit and play on the floor are often bitten in other places as well.

Timing helps too. Bed bugs feed at night, so a new line of bites usually means new marks in the morning. Flea bites can appear at any time of day, often after you have walked across a carpet or sat near a pet's bed.

An adult bed bug is flat, oval and reddish-brown. Oxford City Council gives about 5 mm long and 3 mm wide, and Lambeth Council says up to about 6 mm. It looks like a small seed, and it crawls. Oxford notes that bed bugs do not fly; they get around on foot or by travelling in clothing, luggage, books and furniture.

A cat flea, the type most homes get, is about 2 mm long and dark brown. It is narrow, as though squeezed from side to side, and you rarely see it walk, because it jumps. If something tiny vanishes when you go to touch it, it was probably a flea.

Here is a simple test for fleas: put on long white socks and walk slowly across the carpet, particularly near where a pet sleeps. Dark specks on the socks that move are fleas. For a suspected bed bug, stick the insect to clear tape, then photograph it next to a ruler. A clear photo is often enough for a pest controller to identify it.

Pick a bright moment, take a torch, and work around the bed slowly. You are looking for live insects and for the marks they leave: the NHS lists spots of blood on bedding and small brown spots on bedding or furniture, and Lambeth Council describes the droppings as black dots.

Fleas are easier to confirm if you have an animal at home. Comb your cat or dog with a fine-tooth flea comb over a sheet of white paper, paying attention to the neck and the base of the tail. Cats Protection says you may find a lot of dark flea droppings, known as flea dirt. Dab the specks with damp tissue: if they turn reddish-brown, they are flea dirt rather than soil, because they contain digested blood.

Then check the places the animal rests. Oxford City Council explains that eggs laid on animals fall into carpets and floorboards, and the larvae feed on debris there. Cats Protection says most flea problems come from the home, which is why treating the pet alone often fails. Rugs, sofas, pet beds, car seats and gaps between floorboards are the places to check first.

This one confuses people, particularly just after moving house. Adur & Worthing Councils explain that flea pupae can survive in their cocoons for many months without a host, then emerge when one arrives. Hastings Borough Council puts dormant pupae at up to nine months, while Cats Protection says up to six.

The result is that a flat can look clean, sit empty for weeks, then produce biting fleas within days of someone walking on the carpet. It is not a sign of dirt, or that you brought anything in. A previous tenant's pet, or a visiting cat, is the usual explanation.

Adur & Worthing add that people without pets can also carry fleas home after visiting an infested place. If you have ankle bites and no animal, and no sign of bed bugs around the bed, ask your landlord or agent whether a pet lived there before you.

A few good steps now will help whichever pest it turns out to be, and a few well-meant ones can make things worse. The biggest mistake with bed bugs is moving things. Sleeping on the sofa or in a spare room can take them to a second room, and they will follow you to feed.

For both types, keep the skin clean and try not to scratch, because broken skin can get infected. The NHS suggests a clean, damp cloth to ease itching and swelling, and says bedbug bites usually clear up on their own in a week or so. A pharmacist can advise on a mild steroid cream or an antihistamine. Children under 10 and pregnant women should see a doctor before using hydrocortisone.

See a GP if bites stay very painful, swollen or itchy after a pharmacist's advice, or if the pain or swelling is spreading, as you may need treatment for an infection. Severe allergic reactions to bites are rare, but call 999 if someone has swelling of the lips, mouth or throat, or is struggling to breathe.

Bed bugs are a search-and-treat job. They hide in cracks close to where people sleep and can last a long time between meals: Oxford City Council says they can survive over a year without feeding. Treatment has to reach those hiding places, and usually needs more than one visit. Lambeth Council treats twice, three weeks apart, and Redbridge Council allows two to three visits, 21 to 28 days apart.

Fleas are a floor-and-furnishings job, timed around their life cycle. Hastings Borough Council says the cycle from egg to adult takes 18 to 26 days depending on temperature, and that a single flea can lay up to 25 eggs a day. Pets are treated by the vet at the same time, and the home is treated once, with an insecticide that carries on working if surfaces are left alone.

Preparation matters for both, and a good provider will tell you exactly what to do. For bed bugs, that can mean emptying drawers, pulling furniture away from walls and stripping beds. Bedford Borough Council warns that divan beds may need to be destroyed because they cannot be effectively treated, so ask before you assume yours can be saved.

This is the moment most people panic, and usually it means the treatment is working. Eggs survive. Hastings Borough Council says flea eggs and pupae are not affected by insecticide, so new fleas keep emerging and die when they touch treated surfaces. It calls seeing fleas 10 to 14 days after treatment quite normal, and says to get back in touch if they persist after four weeks.

Bed bugs follow a similar pattern. Oxford says eggs hatch in 10 to 20 days, and Bedford says you may see bugs for several days after treatment as this happens. Both Bedford and Lambeth ask you to keep sleeping in the bed as normal, because bed bugs are drawn to you and cross the treated areas to reach you.

The other rule is to leave the floors alone. Hastings says not to vacuum, sweep or wash floors for at least two weeks after flea treatment, Lambeth says the same for bed bug rooms, and Bedford asks for three weeks. Follow the sheet you are given, because vacuuming early can remove the insecticide.

The rules are the same as for other pests. Citizens Advice says tenants are usually responsible if they caused the problem, and landlords are usually responsible if the tenancy agreement says so, if a failure to repair caused it, or if the infestation makes the home unsafe. Landlords are generally only responsible once they know, so report it straight away, in writing, with your photos.

Bed bugs often arrive in luggage or furniture, which can make the cause hard to prove, and they can move between flats through shared walls. Fleas found soon after you move in point towards the previous occupier. Either way, tell your landlord or agent early and ask your council's environmental health team for advice if you are not getting a response.

Moving out? Keep the treatment record, and read our end of tenancy cleaning checklist. Any carpet left unvacuumed after treatment will need cleaning before the final inspection.

You do not need to work out which pest it is before you contact us. Tell us where the bites are, what you have found and which rooms are affected, and send a photo if you can. We confirm the price, the preparation and the number of visits in writing before any work is booked.

Flea treatment starts from £89. Bed bug treatment starts from £149, which covers one room, plus £45 for each extra room and £79 for each follow-up visit. For comparison, Redbridge Council charges £200 for fleas and £325 for bed bugs in up to three rooms; our Ilford pest control page sets those figures out line by line, and our prices page has the full list.

We are based on Clements Road in Ilford, cover London, and carry public liability insurance. Our phone lines are open Monday to Saturday, 8am to 8pm. If it turns out your problem is scratching in the walls and not bites, see our guide to mice vs rats.