Small Black Bugs in the House
Almost none of these bite, and the room you found them in narrows it to two or three species straight away. Work from where they are rather than from what they look like — at two millimetres, everything looks like a small black bug.
Start with the room, not the insect
Small dark insects are close to impossible to tell apart by eye at that size, and they do not need to be. Each of the common ones lives somewhere specific, so location does most of the identification before you have looked closely at anything.
- On the windowsill in spring, heading for the glass — carpet beetle adults leaving.
- In the kitchen cupboard, in or near dry food — a pantry beetle.
- Around houseplants, flying weakly when the pot is disturbed — fungus gnats.
- On the bathroom wall, fuzzy and moth-like, barely flying — drain flies.
- In damp paper, books or around a window frame, pale rather than black — booklice.
- Jumping when disturbed, near anything damp — springtails, which are harmless and mean moisture.
What it probably is
- Carpet BeetleAnthrenus verbasciTake care
- Spider BeetleMezium americanumHarmless
- Fungus gnatNo record yet
- Drain flyNo record yet
- BookliceNo record yet
- Carpet Beetle. Rounded, 2–3 mm, mottled rather than plain black, and found at windows in spring. Shed larval skins under furniture or in a wardrobe confirm it.
- Spider Beetle. Glossy, almost spherical, with long legs and forward-pointing antennae — often reported as a tiny spider. Comes from old dry food.
- Fungus gnat. Flies, weakly and erratically, and appears when a houseplant is watered. It breeds in wet compost, not in your food.
- Drain fly. Fuzzy, grey-black, moth-shaped, and sits still on bathroom walls. It breeds in the film inside a slow drain.
- Booklice. Under 2 mm, pale grey rather than truly black, soft-bodied, in damp paper or around window frames. Not lice and not on people.
If you still can’t tell
Put a strip of clear tape over a few of them, stick it to white paper and look under a phone camera at full zoom — that beats trying to see them on a skirting board. Then ask two questions: do they fly, and where are they densest? Those two answers separate every insect on this page. If they are in food, discard the packet rather than identifying it precisely; the response is the same for all the pantry species.
Common questions
Are any of these biting me?
None of them bite. If something is genuinely biting, the candidates are fleas, bed bugs or mites, and all three are found by looking at where you sleep rather than at a windowsill. Carpet beetle larvae can cause an itchy rash without ever touching you, which is the usual explanation for bites nobody can find an insect for.
Why are they all at the window?
Insects that have finished feeding indoors head for light to get out. A row of small beetles on a windowsill in spring is usually the end of an infestation rather than the start of one.
Do I need pest control?
Rarely. Fungus gnats need drier compost, drain flies need the drain cleaned, pantry beetles need the source packet found and thrown out. Only carpet beetles in textiles usually justify anything more.
They are jumping. What jumps?
Springtails, almost certainly — they launch with a spring-loaded tail and appear around damp. Fleas also jump, but they jump onto you and springtails do not.
Or just photograph it
If none of these fit, the identifier will take a photo and give you a species, a danger verdict and what it is commonly mistaken for. It says when a photograph cannot settle something rather than guessing — what it can and can’t do.
Where this was checked
- University of California IPM — Carpet Beetles checked 2026-07-30
Last reviewed 2026-07-30.