Hypomecis roboraria
In 3 days ~20% in a week ~40%
Hypomecis roboraria, the great oak beauty, is a moth of the family Geometridae. The species occurs in the Palearctic. The nominate subspecies is found in Europe. The subspecies isabellaria is found in western Central Asia east across Siberia and Mongolia to northern China.
The wingspan is 40–50 mm. The male has feather-shaped antennae, the female thread-shaped. The forewings have three narrow, wavy, dark cross-bands that are clear at the front edge, often blurry further back. The hindwings have two such cross bands, one of which is usually quite clear. The larva is naked, brown and gnarled and strongly resembles a dead oak twig.
The moths fly from May to August. [1] The caterpillars feed on oak. Similar species include Hypomecis punctinalis and Hypomecis sp. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Triglav National Park | 🇸🇮 Slovenia | |
| 2 | Cévennes National Park | 🇫🇷 France | |
| 3 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 4 | Pyrénées National Park | 🇫🇷 France |
With luck
About 10% of wildlife watchers report a Great Oak Beauty sighting in Cévennes National Park on a given day, based on 14 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 493rd most-seen of the 996 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
May and June
In those months about 10% of wildlife watchers report a Great Oak Beauty in Cévennes National Park on a given day, against under 5% in July to April, the lowest months.
Between 10 pm and 1 am
Across all the parks we cover, that three-hour window holds the most Great Oak Beauty sightings with a recorded time, and about 6 in 10 of them come between 6 am and 6 pm: it is seen both by day and at night.
Among the best
Of the 4 parks where we can rate Great Oak Beauty sightings, Cévennes National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Triglav National Park (Slovenia, about 10%).
GBIF citizen-science records
It is estimated from how often the Great Oak Beauty is recorded against all the insects logged in Cévennes National Park (14 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.
