Mosquito bites vs no-see-um bites
Count them. Mosquitoes leave a handful of soft, puffy bumps. No-see-ums — biting midges about a millimetre long — leave dozens of tiny, hard, disproportionately itchy dots, usually on ankles and lower legs after dusk near the coast or a lake.
Side by side
| Mosquito bite | No-see-um bite | |
|---|---|---|
| Looks like | a soft, puffy raised bump (wheal) with a tiny centre dot | tiny red dots that swell into hard, intensely itchy bumps |
| Pattern | single bumps scattered over exposed skin | dozens, clustered on exposed skin |
| Size | 2–20 mm | 1–10 mm |
| Appears | within minutes | a stinging pinprick, then bumps within an hour |
| Lasts | 1 to 3 days, sometimes a week in children | up to two weeks of itch in sensitised people |
| Itch | ●●●●○ 4/5 | ●●●●● 5/5 |
| Pain | ●○○○○ 1/5 | ●●○○○ 2/5 |
| Usually on | ankles, lower legs, arms, neck, face | ankles, lower legs, arms, hairline |
| Active | dusk and dawn for Culex and Anopheles; daytime for Aedes | dawn and dusk, in still air |
| Where from | standing water — gutters, plant saucers, tyres, ponds; they rarely travel far from where they hatched | coastal marsh, mangrove, lakesides and damp soil — abundant in Florida and the Gulf Coast |
| Disease risk | West Nile virus, La Crosse encephalitis, dengue (Gulf Coast and Southwest, local cases), chikungunya (rare, travel-linked) | none known in the US |
What actually settles it
Number and size. Many small hard dots versus a few larger soft bumps.
Did you see anything? Mosquitoes are visible and audible. No-see-ums are not — the name is the description.
Where. Coastal marsh, mangrove, lakesides and damp soil, worst on still evenings. Florida and the Gulf Coast in particular.
Screens. Standard window screens keep mosquitoes out and let no-see-ums straight through. Bites indoors with the screens shut point to midges.
When either one needs a doctor
- fever, headache and neck stiffness within two weeks of a bite
- confusion or unusual drowsiness
- a spreading red area that is hot and painful (possible skin infection)
- spreading redness or pus from scratched bites
- blistering over a wide area
Questions
Can you have both at once?
Yes, and it happens more often than people expect — which is why the pattern of the bites matters more than any single mark.
Which one is more serious?
Mosquito bite carries the wider disease risk in the US. For both, the common complication is infection from scratching.
What if I still cannot tell?
Photograph the bites over several days and note where on your body they appear and when. Progression and position identify a bite far more reliably than a single photograph.
Get a photo assessment in the app
Everything above is free to read. The app adds what a page cannot: point your camera at the bite and get an assessment of the most likely cause, a severity read, and a day-by-day care plan — including the specific signs that mean you should be seen.
iPhone and iPad. Free to download.