Tabanus atratus
In 3 days ~30% in a week ~60%
Tabanus is a genus of biting horseflies of the family Tabanidae. Females have scissor-like mouthparts that are able to penetrate the skin of livestock animals. The horsefly can then extract and ingest the animal's blood. Horseflies of this genus are known to be potential vectors of anthrax, worms and trypanosomes. Some species, such as Tabanus bovinus, prefer bovine animals and are less harmful to humans. The genus contains hundreds of species and many species groups. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Padre Island National Seashore | 🇺🇸 United States | |
| 2 | Merritt Island National Wildlife Refuge | 🇺🇸 United States | |
| 3 | Big Cypress National Preserve | 🇺🇸 United States | |
| 4 | Everglades National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Baltimore | 🇺🇸 United States | |
| 2 | Minneapolis [Saint Paul] | 🇺🇸 United States | |
| 3 | Houston | 🇺🇸 United States | |
| 4 | Washington | 🇺🇸 United States | |
| 5 | Montreal | 🇨🇦 Canada | |
| 6 | Austin | 🇺🇸 United States | |
| 7 | Dallas | 🇺🇸 United States | |
| 8 | Chicago | 🇺🇸 United States | |
| 9 | Toronto | 🇨🇦 Canada | |
| 10 | Philadelphia | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Black Horse Fly sighting in Merritt Island National Wildlife Refuge on a given day, based on 34 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 40th most-seen of the 189 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 60%, if each day is a fresh chance.
September
In that month about 30% of wildlife watchers report a Black Horse Fly in Merritt Island National Wildlife Refuge on a given day, against under 5% in May and December–January, the lowest months. That is one of Merritt Island National Wildlife Refuge's wettest months, with about 210 mm of rain against 50 mm in March.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Black Horse Fly sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
2nd of 4
Of the 4 parks where we can rate Black Horse Fly sightings, Merritt Island National Wildlife Refuge ranks 2nd at about 10%. The best odds are in Padre Island National Seashore (United States, about 20%).
Same order: Diptera
The closest relatives of the Black Horse Fly that you can see in Merritt Island National Wildlife Refuge (order Diptera, Flies) are White-Faced Plushback (about 10%), Common Lovebug (about 10%) and Grallipeza nebulosa (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Black Horse Fly is recorded against all the insects logged in Merritt Island National Wildlife Refuge (34 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
