Biorhiza pallida
In 3 days ~20% in a week ~30%
Biorhiza pallida, also known as the oak apple gall wasp, is a gall wasp species in the family Cynipidae. This species is a member of the tribe Cynipini: the oak gall wasp tribe. Cynipini is the tribe partially responsible for the formation of galls known as oak apples on oak trees. These are formed after the wasp lays eggs inside the leaf buds and the plant tissues swell as the larvae of the gall wasp develop inside. This wasp has a widespread distribution within Europe.
Biorhiza pallida has a complex life cycle involving an agamic female that reproduces by parthenogenesis without a male during the winter/spring, and a summer generation of adults where individuals are either male or female. These mate and produce fertilised eggs.
The wingless agamic wasp is between 4.8 and 6.3 millimetres (0.19 and 0.25 in) long. The head is golden brown with mid-brown eyes and orange ocelli (simple eyes). The long antennae have fifteen segments and are orangeish-brown. The thorax, legs and bulbous, glistening gaster (abdomen) are yellowish-brown.
Male and female wasps that develop in the summer generation are smaller with a length between 2 and 3.5 mm (0.08 and 0.14 in). The head... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 2 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 3 | Sierra de Guadarrama National Park | 🇪🇸 Spain | |
| 4 | Wadden Sea National Park | 🇩🇪 Germany |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | London | 🇬🇧 United Kingdom | |
| 2 | Birmingham | 🇬🇧 United Kingdom | |
| 3 | Liverpool | 🇬🇧 United Kingdom | |
| 4 | Manchester | 🇬🇧 United Kingdom | |
| 5 | Leeds | 🇬🇧 United Kingdom | |
| 6 | Berlin | 🇩🇪 Germany | |
| 7 | Prague | 🇨🇿 Czechia | |
| 8 | Stockholm | 🇸🇪 Sweden | |
| 9 | Essen | 🇩🇪 Germany | |
| 10 | Warsaw | 🇵🇱 Poland |
With luck
About 10% of wildlife watchers report an Oak Apple Gall Wasp sighting in Sierra de Guadarrama National Park on a given day, based on 14 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 244th most-seen of the 597 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 30%, if each day is a fresh chance.
April–May and October
In those months about 10% of wildlife watchers report an Oak Apple Gall Wasp in Sierra de Guadarrama National Park on a given day, against under 5% in June–September and November–March, the lowest months.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Oak Apple Gall Wasp sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 4 parks where we can rate Oak Apple Gall Wasp sightings, Sierra de Guadarrama National Park ranks 3rd at about 10%, level with the leaders once rounded. The best odds are in Snowdonia National Park (United Kingdom, about 10%) and Bavarian Forest National Park (Germany, about 10%).
Same family: Cynipidae
The closest relatives of the Oak Apple Gall Wasp that you can see in Sierra de Guadarrama National Park (family Cynipidae, Gall Wasps) are Andricus quercustozae (about 10%), Mossy Rose Gall Wasp (about 10%) and Common Spangle Gall Wasp (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Oak Apple Gall Wasp is recorded against all the insects logged in Sierra de Guadarrama 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.
