Mesembrina mystacea
In 3 days ~10% in a week ~20%
Mesembrina mystacea is a fly belonging to the family Muscidae. It's commonly referred to as the moustached fly. This species is present in the Palaearctic realm, from Fennoscandia south to Turkey and from the Atlantic seaboard across Eurasia to as far as Mongolia.
Mesembrina mystacea can reach a length of 9–12 millimetres (0.35–0.47 in). These large, distinctive flies are beautifully colored in black, yellow-brown and white. They have a stout body. The long body hairs are mostly black, but they show a band of fine yellow-brown short hairs anteriorly across the thoracic dorsum and dense brown hairs on the abdomen, with white hairs at the edge. Metathorax and abdomen are shiny black. Eyes are bare. A large orange colouration is present on the base of the wings.
The species exhibits a certain sexual dimorphism. In fact the anterior yellow-brown thoracic band of hairs is much narrower in the male than in the female. Moreover, in the male the mid tibiae are curved with longer hairs, while in the females they are straight and without longe hairs.
These flies closely mimic certain Bombus species (bumblebees) (Apidae family). They are very similar to... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Pyrénées National Park | 🇫🇷 France |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Moscow | 🇷🇺 Russia |
Rare
Under 5% of wildlife watchers report a Moustached Fly sighting in Pyrénées National Park on a given day, based on 6 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 1026th most-seen of the 1277 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.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a Moustached Fly in Pyrénées National Park on a given day, so our monthly data shows no clear season.
Between 4 and 7 pm
Across all the parks we cover, that three-hour window holds the most Moustached Fly sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is most active around dawn and dusk.
Only Pyrénées National Park, in our data
Pyrénées National Park is the only park on Wallace's Line with enough records to rate Moustached Fly sightings: under 5% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Moustached Fly is recorded against all the insects logged in Pyrénées 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.
