Maculinea alcon
In 3 days ~10% in a week ~30%
Phengaris alcon, the Alcon blue or Alcon large blue, is a butterfly of the family Lycaenidae and is found in Europe and across the Palearctic to Siberia and Mongolia. L. alcon Schiff. (= areas Esp., euphemus Godt.) (83 a). Large, the male above deep blue, but without brilliant gloss. The female black-brown, dusted with dark blue in the basal area. The dark violet-grey underside has numerous ocelli. L. alcon is easily distinguished from the following species (coeligena [L. coeligena Oberth. China], euphemus, arcas, arion, arionides...) by the male bearing on the blue disc of the forewing no other black spots but the discocellular lunule. Central Europe and North Asia, from the coast of the North Sea (Hamburg, Bremen, Belgium) to the Mediterranean, and from France to the Altai, Dauria and Tibet, ab. nigra Wheel, has the males strongly darkened, the females being quite black above. In ab. cecinae Hormuz. the ocelli of the underside are absent or strongly reduced. In ab. pallidior Schultz the margin is grey instead of black. – marginepunctata Gillm. has a row of black dots before the margin, almost parallel with it; found by Hafner at Loitsch and other places... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Mercantour National Park | 🇫🇷 France | |
| 2 | Cévennes National Park | 🇫🇷 France | |
| 3 | Wadden Sea National Park | 🇩🇪 Germany |
With luck
About 10% of wildlife watchers report an Alcon Large Blue sighting in Cévennes National Park on a given day, based on 10 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 666th most-seen of the 996 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
June to August
In those months about 10% of wildlife watchers report an Alcon Large Blue in Cévennes National Park on a given day, against under 5% in September to May, the lowest months. Those are among Cévennes National Park's driest months, with about 60 mm of rain a month against 260 mm in October.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Alcon Large 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.
2nd of 3
Of the 3 parks where we can rate Alcon Large Blue sightings, Cévennes National Park ranks 2nd at about 10%. The best odds are in Mercantour National Park (France, about 20%).
GBIF citizen-science records
It is estimated from how often the Alcon Large Blue is recorded against all the insects logged in Cévennes National Park (10 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.
