Identify and compare
What is biting me? A UK insect bite identifier
In UK homes, bites are most often from bed bugs, fleas, mosquitoes or biting mites. Bed bug bites tend to appear in lines or clusters on skin exposed in bed; flea bites cluster around ankles and lower legs; mosquito bites are random single welts. The NHS advises that most insect bites are mild and clear up on their own.
Identifying the culprit matters because the fix is completely different: bed bugs need a treatment of the room, fleas usually trace back to a pet, and mosquitoes are about screening and standing water.
Use the table as a starting point. The NHS notes it is often not possible to identify an insect from the bite alone, so look for the insect and other signs too. See a pharmacist or GP if a bite becomes infected or you feel unwell.
At a glance comparison
| Likely culprit | Bite pattern | Where and when | Other signs |
|---|---|---|---|
| Bed bugs | Small itchy bumps in a line or cluster | On skin exposed in bed (arms, shoulders, neck), noticed in the morning | Tiny blood spots or dark specks on bedding, a musty smell, bugs in mattress seams |
| Fleas | Small itchy red bumps, often in clusters of three or four | Around ankles and lower legs, any time | A pet scratching, fleas or flea dirt in pet bedding and carpet |
| Mosquitoes | Single raised itchy welts, random rather than lined up | On exposed skin, often warm evenings near water | You may hear or see the mosquito; standing water nearby |
| Biting mites | Scattered tiny itchy spots | On areas in contact with affected fabric, plants or birds | Often linked to a bird nest, rodents or houseplants rather than the bed |
How to tell them apart
Look at the pattern and where the bites are
Bed bug bites often appear in a rough line or small cluster on skin that was exposed while you slept, and are typically noticed in the morning. Flea bites tend to gather around the ankles and lower legs because fleas live low down in carpets and pet bedding.
Mosquito bites are usually single, random welts on exposed skin, often after a warm evening near standing water. Mite bites are scattered and usually trace back to a source such as a bird nest, rodents or houseplants.
Hunt for the insect, not just the bite
The NHS points out you often cannot tell the insect from the bite alone, so look for corroborating signs: blood spots and dark specks on bedding for bed bugs, a scratching pet and flea dirt for fleas, or a bird nest near a window for mites. Finding the source confirms the bite and points to the fix.
When a bite needs more than self-care
The NHS advises that most bites are mild and settle in a few days. See a pharmacist for itch relief, and contact a GP or NHS 111 if a bite becomes increasingly painful, red, swollen or hot, or if you feel generally unwell, which can signal infection or a reaction.
Frequently asked questions
How do I know if it is bed bugs or fleas biting me?
Bed bug bites tend to appear in lines or clusters on skin exposed in bed and are noticed in the morning, often with blood spots on the bedding. Flea bites usually cluster around the ankles and lower legs and are commonly linked to a pet. Finding the insect confirms which it is.
Can you always tell the insect from the bite?
No. The NHS says it is often not possible to identify which insect caused a bite from the mark alone, because many bites look similar. The pattern, location and timing narrow it down, but looking for the insect and other signs is the surest way to confirm the cause.
When should I see a doctor about a bite?
See a pharmacist for itch relief first. Contact a GP or call NHS 111 if a bite becomes more painful, red, swollen or hot over a day or two, if you develop a spreading rash or fever, or if you feel unwell, as these can indicate infection or an allergic reaction.
What is biting me at night in bed?
Bites that appear overnight on skin exposed in bed, in lines or clusters, point strongly to bed bugs, especially with blood spots or dark specks on the mattress and bedding. Check mattress seams and the bed frame, and read our bed bugs guide before treating the room.
Sources
Editor, HomesAndHedge
Oliver leads HomesAndHedge's editorial coverage of home and garden problems. He researches and writes the plain-English explainers on pests, invasive plants, damp and mould, drainage and wildlife, drawing on guidance from bodies such as the Property Care Association, the RHS and the NHS, and is clear about when a job needs a qualified professional.
Last reviewed: 8 June 2026