Hippobosca equina
In 3 days ~20% in a week ~50%
Hippobosca equina, also known as the forest fly or New Forest fly, is a biting fly from the family Hippoboscidae. They are blood-feeding ectoparasites of primarily horses and other large mammals including cattle. It is a permanently fully winged fly, not shedding its wings on finding its host, as in some other Hippoboscidae. With its wings retained, it may thus fly away from its host to deposit its larvae. They are good fliers.
Wing length 6.0–8.5 millimetres (0.24–0.33 in). Generally pale reddish brown with yellow spots on the indistinctly segmented abdomen. They have one pair of sub-triangular wings and the wing veins are crowded together towards the anterior border.
The characteristic feature of these flies is that they move sidewards and they feed preferably between the hind legs and on the perineum region. The New Forest fly lays larvae singly in late instar (stage III). They rapidly pupate over one hour and exhibit varying duration as pupae, depending on temperature.
The primary distribution is in Europe and parts of Asia and Africa. It has been introduced to other locations, though in some cases latter eradicated by modern... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sierra Nevada National Park | 🇪🇸 Spain | |
| 2 | Pyrénées National Park | 🇫🇷 France | |
| 3 | Cévennes National Park | 🇫🇷 France | |
| 4 | Sierra de Guadarrama National Park | 🇪🇸 Spain |
With luck
About 10% of wildlife watchers report a New Forest Fly sighting in Sierra Nevada National Park on a given day, based on 6 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 330th most-seen of the 479 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.
June and July
In those months about 20% of wildlife watchers report a New Forest Fly in Sierra Nevada National Park on a given day, against under 5% in August and October–May, the lowest months.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most New Forest Fly sightings with a recorded time, and about 6 in 10 of them come between 6 am and 6 pm: it is seen both by day and at night.
Yes
Of the 4 parks where we can rate New Forest Fly sightings, Sierra Nevada National Park has the highest daily chance: about 10%. Next come Pyrénées National Park (France, about 10%) and Cévennes National Park (France, under 5%).
Same order: Diptera
The closest relatives of the New Forest Fly that you can see in Sierra Nevada National Park (order Diptera, Flies) are Common Drone Fly (about 20%), Hornet Mimic Hover Fly (about 20%) and Dryomyia lichtensteinii (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the New Forest Fly is recorded against all the insects logged in Sierra Nevada National Park (6 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.
