Stomoxys calcitrans
In 3 days ~10% in a week ~20%
Stomoxys calcitrans is known by the common names stable fly, barn fly, biting house fly, dog fly, and power mower fly. Unlike most members of the family Muscidae, Stomoxys calcitrans ('sharp mouth' + 'kicking') and others of its genus suck blood from mammals. Now found worldwide, the species is considered to be of Eurasian or African origin.
The stable fly resembles the common housefly (Musca domestica), though smaller, and on closer examination has a slightly wider and spotted abdomen. Adults are generally about 6–8 mm (1⁄4–5⁄16 inch) in length and a lighter color than the housefly. Unlike the housefly, where the mouth part is adapted for sponging, the stable fly mouth parts have biting structures. An additional distinction from M. domestica is in the aristae, which bear a single, superior row of hairs in S. calcitrans instead of two opposing rows.
As its name suggests, the stable fly is abundant in and around where cattle are kept. Its maggots are often seen in the rotting manure near cattle and poultry. It also occurs in coastal areas where larvae may inhabit masses of decaying aquatic vegetation deposited ashore.
The earliest... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Point Pelee National Park | 🇨🇦 Canada | |
| 2 | Great Smoky Mountains National Park | 🇺🇸 United States | |
| 3 | Wadden Sea National Park | 🇩🇪 Germany |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Quito | 🇪🇨 Ecuador | |
| 2 | San Luis Potosí | 🇲🇽 México | |
| 3 | Boston | 🇺🇸 United States | |
| 4 | Lima | 🇵🇪 Peru | |
| 5 | Porto | 🇵🇹 Portugal | |
| 6 | Lisbon | 🇵🇹 Portugal | |
| 7 | Baltimore | 🇺🇸 United States | |
| 8 | Auckland | 🇳🇿 New Zealand | |
| 9 | New York City | 🇺🇸 United States | |
| 10 | Sacramento | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Stable Fly sighting in Wadden Sea National Park on a given day, based on 9 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 536th most-seen of the 818 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
October
In that month about 10% of wildlife watchers report a Stable Fly in Wadden Sea National Park on a given day, against under 5% in November to September, the lowest months. That is one of Wadden Sea National Park's wettest months, with about 120 mm of rain against 45 mm in April.
Between 1 and 4 pm
Across all the parks we cover, that three-hour window holds the most Stable 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.
3rd of 3
Of the 3 parks where we can rate Stable Fly sightings, Wadden Sea National Park ranks 3rd at under 5%. The best odds are in Point Pelee National Park (Canada, about 10%) and Great Smoky Mountains National Park (United States, under 5%).
GBIF citizen-science records
It is estimated from how often the Stable Fly is recorded against all the insects logged in Wadden Sea National Park (9 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.
