Polyommatus icarus
In 3 days ~40% in a week ~70%
The common blue butterfly or European common blue (Polyommatus icarus) is a butterfly in the family Lycaenidae and subfamily Polyommatinae. The butterfly is found throughout the Palearctic and has been introduced to North America. Butterflies in the Polyommatinae are collectively called blues, from the coloring of the wings. Common blue males usually have wings that are blue above with a black-brown border and a white fringe. The females are usually brown above with a blue dusting and orange spots.
The Common blue was elected as the national butterfly of Israel in 2023. The contest was launched by the National Butterfly Lovers of Israel Association, with the participation of other nature organizations. A factor in the election result is that like Polyommatus icarus, the flag of Israel is blue and white.
This species was first described by Siegmund Adrian von Rottemburg in 1775. Vernacular names that have been given to P. icarus include little blew argus, blew argus, mixed argus, selvedg'd argus, ultramarine blue, caerulean butterfly, and alexis.
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| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Kiskunság National Park | 🇭🇺 Hungary | |
| 2 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 3 | Cévennes National Park | 🇫🇷 France | |
| 4 | Picos de Europa National Park | 🇪🇸 Spain | |
| 5 | Hortobágy National Park | 🇭🇺 Hungary | |
| 6 | Mercantour National Park | 🇫🇷 France | |
| 7 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 8 | Aigüestortes National Park | 🇪🇸 Spain | |
| 9 | Plitvice Lakes National Park | 🇭🇷 Croatia | |
| 10 | Wadden Sea National Park | 🇩🇪 Germany | |
| 11 | Pyrénées National Park | 🇫🇷 France | |
| 12 | Cairngorms National Park | 🇬🇧 United Kingdom | |
| 13 | Biebrza National Park | 🇵🇱 Poland | |
| 14 | Ordesa y Monte Perdido National Park | 🇪🇸 Spain | |
| 15 | Fertő-Hanság National Park | 🇭🇺 Hungary | |
| 16 | Triglav National Park | 🇸🇮 Slovenia | |
| 17 | Camargue | 🇫🇷 France | |
| 18 | Białowieża National Park | 🇵🇱 Poland | |
| 19 | Sierra de Guadarrama National Park | 🇪🇸 Spain | |
| 20 | Ecrins National Park | 🇫🇷 France | |
| 21 | Sierra Nevada National Park | 🇪🇸 Spain |
With luck
About 10% of wildlife watchers report a Common Blue sighting in Białowieża National Park on a given day, based on 9 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 71st most-seen of the 158 insects we can rate there. Over three days the chance rises to about 40%, and over a week to about 70%, if each day is a fresh chance.
August
In that month about 30% of wildlife watchers report a Common Blue in Białowieża National Park on a given day, against under 5% in September to April, the lowest months.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Common 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.
18th of 21
Of the 21 parks where we can rate Common Blue sightings, Białowieża National Park ranks 18th at about 10%. The best odds are in Kiskunság National Park (Hungary, about 40%), Bavarian Forest National Park (Germany, about 30%) and Cévennes National Park (France, about 30%). All parks ranked.
Same family: Lycaenidae
The closest relatives of the Common Blue that you can see in Białowieża National Park (family Lycaenidae, Gossamer-winged Butterflies) are Scarce Copper (about 30%), Sooty Copper (about 20%) and Large Copper (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Common Blue is recorded against all the insects logged in Białowieża National Park (9 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.
