Chlorotabanus crepuscularis
In 3 days ~20% in a week ~50%
Chlorotabanus crepuscularis is a species of horse flies in the family Tabanidae. This species is the only green tabanid in North America. It can be found from Texas to Delaware. In Florida, this sanguinivorous (blood-feeding) fly is seen as an adult from March through September, but is most active from May to mid-July.
The female has the ability to sense carbon dioxide, which helps it feed on mammals, especially during the night when it is most active. The larvae are also predaceous and live in the soil adjacent to water and on floating vegetation but can also live in forest sand. The insect's blood is blue. The fly's eyes are brown, but glow yellow under 385 nm UV light. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Big Cypress National Preserve | 🇺🇸 United States | |
| 2 | Everglades National Park | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Green Horse Fly sighting in Big Cypress National Preserve on a given day, based on 10 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 154th most-seen of the 262 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 50%, if each day is a fresh chance.
May
In that month about 30% of wildlife watchers report a Green Horse Fly in Big Cypress National Preserve on a given day, against under 5% in July to April, the lowest months.
Between 5 and 8 am
Across all the parks we cover, that three-hour window holds the most Green Horse Fly sightings with a recorded time, and about 6 in 10 of them come between 6 pm and 6 am: it is most active around dawn and dusk.
Yes
Of the 2 parks where we can rate Green Horse Fly sightings, Big Cypress National Preserve has the highest daily chance: about 10%. Next come Everglades National Park (United States, about 10%).
Same family: Tabanidae
The closest relatives of the Green Horse Fly that you can see in Big Cypress National Preserve (family Tabanidae, Horse and Deer Flies) are Black Horse Fly (about 10%) and Yellow Fly Of The Dismal Swamp (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Green Horse Fly is recorded against all the insects logged in Big Cypress National Preserve (10 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.
