Bed bug bite

A bed bug bite usually shows up as firm, flat-topped welts, often with a darker centre, red and inflamed, darker on deeper skin tones, appearing hours to several days — many people notice nothing on the first night. It peaks around day 2 to 3 and generally lasts 1 to 2 weeks. Lines or zigzags of three or more — the classic "breakfast, lunch and dinner" is the usual arrangement.

How to tell it apart

The pattern is the tell. Bed bugs feed in a straight or slightly curved line because the insect probes, is disturbed, moves a few millimetres and feeds again — so you get three or four welts along a line on skin that was uncovered at night. The second tell is timing: bites appear on the same body areas over consecutive mornings, and they show up on people sleeping in that bed and nobody else.

Where and when you meet it

Habitat: mattress seams, bed frames, headboards, sofa joints, luggage; they hide within a few metres of where you sleep.

Across 1,029 verified US records in the GBIF biodiversity database, sightings of Cimex lectularius concentrate in July. That is the window when bites are most likely — it is observation data rather than a guess, and it shifts with latitude.

States with the most recorded sightings

• California 184 records
• Illinois 81 records
• Texas 65 records
• Pennsylvania 41 records
• Indiana 36 records
• Colorado 35 records
• Ohio 35 records
• Alaska 30 records
• Minnesota 29 records
• Michigan 28 records
• North Carolina 26 records
• South Carolina 25 records

Record counts reflect where people report and identify specimens, not exact abundance. They are useful for ruling a species in, not for ruling it out.

Where it is recorded

Verified records from the GBIF biodiversity database across the seven countries we cover. A country missing from this table means we have no records for it, not that the species is absent.

What it means for you

Bed bugs carry no known human disease. That fact does not make them harmless — the sleep loss, the anxiety and the cost of eradication are the real damage, and a heavy infestation can cause anaemia in vulnerable people. Roughly a third of people never develop a visible mark at all, which is why an unbitten partner in the same bed proves nothing.

Care at home

1. wash with soap and water
2. antihistamine or steroid cream for the itch
3. treat the room, not just the skin — bites stop only when the insects are gone
4. wash and tumble-dry bedding on high heat

Preventing the next one

• inspect mattress seams and headboards in hotels before unpacking
• keep luggage off the bed and floor
• encasements on mattress and box spring
• professional treatment for an established infestation — retail sprays rarely finish the job