Deer flies in Wisconsin
Yes — deer flies are recorded in Wisconsin. The GBIF biodiversity database holds 98 verified deer fly records from the state — ranking it 6th nationally. Sightings concentrate in June to July. Onset: immediate sharp pain. Duration: a few days.
| Verified records | 98 |
|---|---|
| Peak sightings | June to July |
| State bite season | May to September |
| Active | daylight hours, worst in humid weather near water |
| Habitat | wetlands, lakesides, wooded trails |
| Bite appears | immediate sharp pain |
Deer fly bites in Wisconsin: what the mark looks like
Deer flies circle the head and bite the scalp and neck, which distinguishes them from horseflies going for legs and back. The patterned wings and gold-green eyes are visible when one lands.
Locally, the species most often confused with it are bald-faced hornet sting — all of which are also recorded in Wisconsin.
Seek medical care if
- spreading redness and warmth
- fever with swollen glands after a bite
What else it could be in Wisconsin
These are recorded in Wisconsin too and are the ones most often confused with it here. The differences below are the ones that actually separate them.
| Deer fly bite | Black fly bite | Horsefly bite | |
|---|---|---|---|
| Pattern | single or a few, often on the scalp and neck | several, along the hairline, ears and ankles | single, occasionally two |
| Where on body | scalp, neck, shoulders — they target the highest point of a moving person | hairline, behind the ears, ankles | legs, back, shoulders — often through thin clothing |
| Appears | immediate sharp pain | often painless at first, itch builds over hours | immediate, sharp — you feel this one |
| Records here | 98 | 99 | 98 |
Deer fly season in Wisconsin specifically
Records in Wisconsin concentrate in June to July, which is what local sighting data shows rather than a national average — seasonality shifts substantially with latitude. The general bite season in Wisconsin runs May to September.
Because wetlands, lakesides, wooded trails, exposure in Wisconsin tends to be concentrated in specific places rather than spread evenly — which is why a bite history ("where were you in the 24 hours before?") narrows the answer faster than the appearance of the mark.
Month by month in Wisconsin
These are the 98 Wisconsin records broken out by the month they were recorded — not a national curve redrawn for the state. Records appear in 4 of the 12 months here. The single busiest month is July with 44 records (45% of the state total).
| Month | Records | Share |
|---|---|---|
| May | 9 | 9% |
| June | 42 | 43% |
| July | 44 | 45% |
| August | 2 | 2% |
Counts are observations submitted to GBIF, not bites. They tell you when the animal is out and being noticed in Wisconsin; they do not tell you how many people were bitten. The thinnest month with any record at all is August (2).
How Wisconsin compares
Across the 40 states with any deer fly records, Wisconsin ranks 6th with 98. The state directly above it is South Carolina (112). Directly below is Maryland (94). The highest count anywhere is Indiana (419).
Inside Wisconsin itself the picture is different again: of the 18 biting species we track with records here, this one is 11th and accounts for 1% of the 9,394 records logged in the state. A species can be common nationally and marginal in one state, or the reverse — which is the whole reason this page exists separately from the national guide.
Care
- wash, cold pack, antihistamine
- keep the site clean
Avoiding deer flies in Wisconsin
- hats and light-coloured clothing
- sticky patches on caps work surprisingly well on trails
- repellent has limited effect
Questions
Are there deer flies in Wisconsin?
Yes. Wisconsin accounts for 98 verified records in GBIF, ranking it 6th among the 40 states with any records for this species, just behind South Carolina (112). Within Wisconsin it is 11th of the 18 biting species we track here, at 1% of the state's records. Records reflect reporting effort as well as abundance.
When are deer flies active in Wisconsin?
Wisconsin records peak in June to July. The general bite season in Wisconsin runs May to September.
What does the bite look like?
a painful red weal, smaller than a horsefly bite, red. Single or a few, often on the scalp and neck.
Which month has the most sightings in Wisconsin?
July, with 44 of the 98 Wisconsin records (45%). Records appear in 4 of the 12 months here. This counts sightings submitted to GBIF, not bites.
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.
Download on the App Store — free
iPhone and iPad · Free to download · No account needed