- After feeding it swells, gets longer and turns a darker red.
- Young bed bugs (nymphs) are 1.5 to 4.5mm and pale, straw coloured or see-through.
- Eggs are about 1mm, pearly white, and stuck in clusters in seams and cracks.
Bed bugs at every life stage
Pearly white, slightly curved, glued in clusters. Hatches in about 6 to 10 days.
See-through and straw coloured. A fed nymph shows a bright red dot of blood inside.
Tan to light brown. Moults five times, leaving a pale skin each time.
Flat, oval, reddish brown, no wings. Swollen and darker after a meal.
Unfed vs fed
An unfed adult is as flat as a lentil, which is how it fits into seams and cracks as thin as a credit card. After feeding for 5 to 10 minutes it becomes longer, rounder and dark red, and it heads straight back to its hiding place.
How to tell at a glance
- Shape: oval and flat from above, not round like a beetle.
- Colour: rusty or reddish brown, never black and white.
- Wings: none. Bed bugs cannot fly or jump; they crawl.
- Where: mattress seams, bed frame joints, headboard, within about 2 metres of the bed.
Is it a bed bug? Free identifier
Shape
Colour
What did it do?
Where was it?
Bugs that look like bed bugs
| Bug | How it differs from a bed bug |
|---|---|
| Carpet beetle (adult) | Round not oval, mottled black, white and brown, 2 to 4mm, can fly. Full comparison |
| Carpet beetle larva | Long, hairy and striped brown; lives in carpet edges and wardrobes; does not bite but its hairs can cause a rash. |
| Flea | Narrow, dark, squashed side to side, and jumps. |
| Booklouse | 1 to 2mm, pale grey, darts quickly, lives near damp paper and windows. Harmless. |
| Spider beetle | Round and shiny like a tiny spider, found in food cupboards. |
| Dust mite | Invisible to the naked eye (about 0.25mm). If you can see it, it is not a dust mite. Read about tiny bugs in bed that are not bed bugs. |
What bed bug signs look like
You are more likely to find the signs than the bugs. Look for dark ink-like dots that smear, rusty spots on sheets, pale shed skins and clusters of white eggs in the mattress seams. Our signs of bed bugs guide includes a 10 minute check and a free checker.
Found one? What to do next
- Catch it on clear tape and stick it to white paper. A pest controller can confirm it from that.
- Do not move rooms. Bag and hot wash bedding at 60°C.
- Check the mattress seams and bed frame with a torch.
- Seal the mattress in a full-zip encasement so anything inside is trapped.
- Follow the full 8 step plan.
Frequently asked questions
Can bed bugs fly or jump?
No. They crawl, quite slowly. Anything that flies or jumps is not a bed bug.
Are bed bugs visible to the human eye?
Yes. Adults are clearly visible at 5 to 7mm. Eggs and young nymphs are tiny and pale, so use a torch and look closely along seams.
What colour are bed bugs?
Adults are reddish brown, darker red after feeding. Nymphs are pale, straw coloured or see-through until they feed.
Do bed bugs have a smell?
A large infestation can give off a sweet, musty smell. Small ones usually have no noticeable smell.
Confirmed it? Trap them in the mattress
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Shop the bed bug encasement Protect the whole bedWritten by Richard Williams, founder of iDustMite, former NHS worker, guest speaker at the Allergy UK Show in 2025 and 2026, and adviser on over 1,000 one-to-one bedroom consultations. Reviewed October 2026.
