Urophora cardui
In 3 days ~20% in a week ~30%
Urophora cardui or the Canada thistle gall fly is a fruit fly which, contrary to its common name, is indigenous to Central Europe from the United Kingdom east to near the Crimea, and from Sweden south to the Mediterranean. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Wadden Sea National Park | 🇩🇪 Germany |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Manchester | 🇬🇧 United Kingdom | |
| 2 | Birmingham | 🇬🇧 United Kingdom | |
| 3 | Toronto | 🇨🇦 Canada | |
| 4 | London | 🇬🇧 United Kingdom | |
| 5 | Denver | 🇺🇸 United States | |
| 6 | Portland | 🇺🇸 United States | |
| 7 | Montreal | 🇨🇦 Canada | |
| 8 | Chicago | 🇺🇸 United States | |
| 9 | Baltimore | 🇺🇸 United States | |
| 10 | Saint Petersburg | 🇷🇺 Russia |
With luck
About 10% of wildlife watchers report a Thistle Stem Gall Fly sighting in London on a given day, based on 54 verified sightings from GBIF citizen-science data. It is the 442nd most-seen of the 1504 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 30%, if each day is a fresh chance.
March and July–October
In those months about 10% of wildlife watchers report a Thistle Stem Gall Fly in London on a given day, against under 5% in April–June and November–February, the lowest months.
Between 1 and 4 pm
Across all the parks we cover, that three-hour window holds the most Thistle Stem Gall 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 13 cities where we can rate Thistle Stem Gall Fly sightings, London ranks 4th at about 10%, level with the leaders once rounded. The best odds are in Manchester (United Kingdom, about 10%), Birmingham (United Kingdom, about 10%) and Toronto (Canada, about 10%).
GBIF citizen-science records
It is estimated from how often the Thistle Stem Gall Fly is recorded against all the insects logged in London (54 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.
