Dioctria hyalipennis
In 3 days ~20% in a week ~50%
Dioctria hyalipennis is a Holarctic species of robber fly in the family Asilidae. 10 to 14 mm. The upper head and vertex are shiny black. The lower face has a silvery-white pile. The mystax is white and the short proboscis black. The antennae appears Y-shaped with the segments about equal in length. They are black with short black hair. The neck is obvious and the thorax is raised or humped. It is black with two long indented lines and a faint covering of light yellow pile. Segment 2 (scutellum) is small with a line of yellow pile at the base. The thorax sides have a wide stripe of whitish pollen extending along the thorax down to the front leg.
The wings are hyaline, but appear darker when folded over the body. The veins are brown. Halteres light yellow. The front and middle legs are mostly yellow with black streaks on the top side and dark tips. The feet are black with grey piles and yellow spines and toes. The hind legs are black with a swollen 1st foot segment.
The abdomen is shining black. The lower margin of segments has a thin whitish line. The first 4 male segments are very narrow and constricted (appear wavy); the last few segments gradually widen to the... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Acadia National Park | 🇺🇸 United States | |
| 2 | Bavarian Forest National Park | 🇩🇪 Germany |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Boston | 🇺🇸 United States | |
| 2 | Toronto | 🇨🇦 Canada | |
| 3 | Birmingham | 🇬🇧 United Kingdom | |
| 4 | Berlin | 🇩🇪 Germany | |
| 5 | Montreal | 🇨🇦 Canada | |
| 6 | Hamburg | 🇩🇪 Germany | |
| 7 | London | 🇬🇧 United Kingdom | |
| 8 | Essen | 🇩🇪 Germany | |
| 9 | Detroit | 🇺🇸 United States | |
| 10 | Seattle | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Stripe-Legged Robber Fly sighting in Acadia National Park on a given day, based on 23 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 116th most-seen of the 405 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.
July
In that month about 20% of wildlife watchers report a Stripe-Legged Robber Fly in Acadia National Park on a given day, against under 5% in August to May, the lowest months.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Stripe-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.
Yes
Of the 2 parks where we can rate Stripe-Legged Robber Fly sightings, Acadia National Park has the highest daily chance: about 10%. Next come Bavarian Forest National Park (Germany, about 10%).
GBIF citizen-science records
It is estimated from how often the Stripe-Legged Robber Fly is recorded against all the insects logged in Acadia National Park (23 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.
