Cosmorhoe ocellata
In 3 days ~30% in a week ~50%
Cosmorhoe is a monotypic genus of moth in the family Geometridae erected by Jacob Hübner in 1825. Its only species, Cosmorhoe ocellata, the purple bar, was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae.
The species can be found in the Palearctic realm, which includes western Europe and the British Isles, Central Europe, Central Asia, Asia Minor, and Kyrgyzstan. In the Alps, it can be found at elevations up to 1500 meters. The species is found in many habitats, including heathland, deciduous and mixed forests, forest clearings, bushy places, grasslands, fens, scrub, gardens and park-like landscapes.
Their wingspan is between 20 and 29 mm and the length of their forewings is between 13 and 15 mm. The ground colour of the forewings is creamy white to bright white. The base and midfield are coloured black to blue black. The latter is crossed by two bright lines. In the midfield band is a deep, jagged spot. In the bright areas between the basal area and the midfield as well as in the marginal field are grey or black spots of varying degrees. The hindwings are whitish and show a small black middle spot.
Caterpillars... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 2 | Cairngorms National Park | 🇬🇧 United Kingdom | |
| 3 | Vanoise National Park | 🇫🇷 France | |
| 4 | Pyrénées National Park | 🇫🇷 France | |
| 5 | Cévennes National Park | 🇫🇷 France | |
| 6 | Wadden Sea National Park | 🇩🇪 Germany | |
| 7 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 8 | Sierra de Guadarrama National Park | 🇪🇸 Spain |
With luck
About 10% of wildlife watchers report a Purple Bar sighting in Cairngorms National Park on a given day, based on 16 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 100th most-seen of the 300 insects we can rate there. Over three days the chance rises to about 30%, and over a week to about 50%, if each day is a fresh chance.
July–August and November
In those months about 20% of wildlife watchers report a Purple Bar in Cairngorms National Park on a given day, against under 5% in September–October and December–May, the lowest months.
Between 10 pm and 1 am
Across all the parks we cover, that three-hour window holds the most Purple Bar sightings with a recorded time, and about 6 in 10 of them come between 6 pm and 6 am: it is seen both by day and at night.
Among the best
Of the 8 parks where we can rate Purple Bar sightings, Cairngorms National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Snowdonia National Park (United Kingdom, about 10%).
Same family: Geometridae
The closest relatives of the Purple Bar that you can see in Cairngorms National Park (family Geometridae, Geometer Moths) are Chimney-Sweeper (about 20%), Bordered White (about 20%) and Common Heath (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Purple Bar is recorded against all the insects logged in Cairngorms National Park (16 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.
