Tachina grossa
In 3 days ~20% in a week ~40%
Tachina grossa is a very large tachinid fly. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cairngorms National Park | 🇬🇧 United Kingdom | |
| 2 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 3 | Cévennes National Park | 🇫🇷 France | |
| 4 | Pyrénées National Park | 🇫🇷 France | |
| 5 | Wadden Sea National Park | 🇩🇪 Germany |
With luck
About 10% of wildlife watchers report a Yellow-Faced Fly sighting in Snowdonia National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 336th most-seen of the 387 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
June to August
In those months about 10% of wildlife watchers report a Yellow-Faced Fly in Snowdonia National Park on a given day, against under 5% in September to May, the lowest months.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Yellow-Faced 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.
Among the best
Of the 5 parks where we can rate Yellow-Faced Fly sightings, Snowdonia National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Cairngorms National Park (United Kingdom, about 10%).
Same order: Diptera
The closest relatives of the Yellow-Faced Fly that you can see in Snowdonia National Park (order Diptera, Flies) are Tapered Drone Fly (about 20%), Marmalade Hover Fly (about 20%) and Dark Giant Horse Fly (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Yellow-Faced Fly is recorded against all the insects logged in Snowdonia National Park (5 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.
