Dioctria atricapilla
In 3 days ~10% in a week ~20%
Dioctria atricapilla, the violet black-legged robber fly, is a species of robber fly in the subfamily Dasypogoninae. This 9- to 12-millimeter long insect has a wingspan of roughly 7 to 9 mm and short, three-segmented antennae. It's a predatory insect, feeding mainly on smaller flies and predatory hymenopterans. It primarily thrives in grassland, and is seen from May to July.
Like all robber flies, the violet black-legged robber fly feed by perching on lower stems of grasses and attack prey as it flies by. The larvae usually grow up in dung piles or decaying organic matter, but they can also be in regular soil.
Courting behavior involves the male leading the courtship dance in front of the female. If she isn't impressed, she'll rapidly move her wings or fly away; otherwise the male will begin copulating. There are 24 locations in the United Kingdom where it's a protected species, mostly in England. It can be found throughout European and east Palearctic grasslands.
Difficult to distinguish from other Dioctria. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Warsaw | 🇵🇱 Poland | |
| 2 | London | 🇬🇧 United Kingdom | |
| 3 | Birmingham | 🇬🇧 United Kingdom |
Rare
Under 5% of wildlife watchers report a Violet Black-Legged Robber Fly sighting in London on a given day, based on 20 verified sightings from GBIF citizen-science data. It is the 776th most-seen of the 1504 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.
May and June
In those months about 10% of wildlife watchers report a Violet Black-Legged Robber Fly in London on a given day, against under 5% in July to April, the lowest months.
Between 4 and 7 pm
Across all the parks we cover, that three-hour window holds the most Violet Black-Legged Robber 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.
2nd of 3
Of the 3 cities where we can rate Violet Black-Legged Robber Fly sightings, London ranks 2nd at under 5%. The best odds are in Warsaw (Poland, about 10%).
GBIF citizen-science records
It is estimated from how often the Violet Black-Legged Robber Fly is recorded against all the insects logged in London (20 verified sightings), 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.
