Polyommatus thersites
In 3 days ~10% in a week ~20%
Polyommatus thersites, the Chapman's blue, is a butterfly in the family Lycaenidae. It is found in southern Europe, Morocco, Lebanon, Asia Minor, Iran and across the Palearctic to Siberia and Tian Shan. It is a small butterfly with both generation dimorphism and sexual dimorphism. For the first generation the upperside is blue with grey hind-wings and in the female a sub-marginal line of orange spots. The summer generation of the female is brown with the same sub-marginal line of orange spots while they are absent in the lighter male.
Representatives of both sexes have in the spring generation grey-colored hindwing undersides while (sandy brown in the summer generation). The underside is ochre marked with black dots circled in white and decorated with a sub-marginal line of orange spots. The forewing underside is yellow grey in summer females.
Polyommatus thersites is similar to Polyommatus icarus, but they are smaller and both sexes have no basal spots on the underside of the forewing. The larva feeds on Onobrychis species (O. arenaria, O. peduncularis, O. sativa and O. viciifolia) Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Vanoise National Park | 🇫🇷 France | |
| 2 | Cévennes National Park | 🇫🇷 France |
Rare
Under 5% of wildlife watchers report a Chapman's Blue sighting in Vienna on a given day, based on 5 verified sightings from GBIF citizen-science data. It is the 1286th most-seen of the 1406 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 Chapman's Blue in Vienna on a given day, so our monthly data shows no clear season.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Chapman's Blue 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 2 cities where we can rate Chapman's Blue sightings, Vienna ranks 2nd at under 5%, level with the leaders once rounded. The best odds are in Prague (Czechia, under 5%).
GBIF citizen-science records
It is estimated from how often the Chapman's Blue is recorded against all the insects logged in Vienna (5 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.
