Tortrix viridana
In 3 days ~10% in a week ~30%
The green oak tortrix, Tortrix viridana, also known as the European oak leafroller and the green oak moth, is a distinctive green moth whose larvae feed on tree leaves, especially oak. The head, forebody and front wings are green, the hind wings lightly greyish. The wingspan is 18-24 millimetres.
An infestation of the larvae can defoliate an oak tree. The adult female lays its eggs next to leaf buds, which the larvae consume when they emerge. As the larvae grow bigger they eat larger leaves, and then roll themselves up in a full-sized leaf to pupate.
Larvae occur from April to June; adults are on wing in June and July. The Ichneumon wasp Dirophanes invisor is a parasitoid which specializes on T. viridana. They are commonly found in many parts of Britain. In the Butterfly Conservation’s Microlepidoptera Report 2011 this species was classified as common. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cévennes National Park | 🇫🇷 France | |
| 2 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 3 | Wadden Sea National Park | 🇩🇪 Germany | |
| 4 | Sierra de Guadarrama National Park | 🇪🇸 Spain |
Rare
Under 5% of wildlife watchers report a Green Oak Tortrix sighting in Sierra de Guadarrama National Park on a given day, based on 10 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 325th most-seen of the 597 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.
May and June
In those months about 10% of wildlife watchers report a Green Oak Tortrix in Sierra de Guadarrama National Park on a given day, against under 5% in July to April, the lowest months.
Between 6 and 9 am
Across all the parks we cover, that three-hour window holds the most Green Oak Tortrix sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is most active around dawn and dusk.
4th of 4
Of the 4 parks where we can rate Green Oak Tortrix sightings, Sierra de Guadarrama National Park ranks 4th at under 5%. The best odds are in Cévennes National Park (France, about 10%), Snowdonia National Park (United Kingdom, about 10%) and Wadden Sea National Park (Germany, about 10%).
GBIF citizen-science records
It is estimated from how often the Green Oak Tortrix is recorded against all the insects logged in Sierra de Guadarrama 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.
