Andricus kollari
In 3 days ~20% in a week ~30%
Andricus kollari, also known as the marble gall wasp, is a species of wasp which causes the formation of marble galls on oak trees. Synonyms for the species include Cynips kollari, Andricus quercusgemmae, A. minor, A. indigenus and A. circulans.
Adult Andricus kollari are dark brown, and about 1.5–2.0 millimetres (0.059–0.079 in) in length. It has alternating sexual and asexual generations, each often taking two years to complete. Like all gall wasps, it causes the formation of parasitic galls on trees in which it lays its larvae.
In May or June, a sexual female lays her eggs in the developing buds of susceptible oak trees using her ovipositor. Chemicals produced by both the adult and developing wasps cause the formation of a gall. Pedunculate oak (Quercus robur), sessile oak (Q. petraea) and the hybrid Quercus × rosacea can all be parasitized. The host trees are often immature or retarded specimens; galls are rarer on older, healthier trees. The Turkey oak (Q. cerris), introduced into Britain in 1735, is required for the completion of the wasp's life cycle. The oak marble gall is frequently conflated with the oak apple gall, caused by another gall wasp, Biorhiza... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 2 | Wadden Sea National Park | 🇩🇪 Germany | |
| 3 | Cévennes National Park | 🇫🇷 France | |
| 4 | Pyrénées National Park | 🇫🇷 France | |
| 5 | Sierra de Guadarrama National Park | 🇪🇸 Spain |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Liverpool | 🇬🇧 United Kingdom | |
| 2 | London | 🇬🇧 United Kingdom | |
| 3 | Birmingham | 🇬🇧 United Kingdom | |
| 4 | Manchester | 🇬🇧 United Kingdom | |
| 5 | Dublin | 🇮🇪 Ireland | |
| 6 | Amsterdam | 🇳🇱 Netherlands | |
| 7 | Rotterdam [The Hague] | 🇳🇱 Netherlands | |
| 8 | Paris | 🇫🇷 France | |
| 9 | Prague | 🇨🇿 Czechia | |
| 10 | Munich | 🇩🇪 Germany |
With luck
About 10% of wildlife watchers report an Oak Marble Gall Wasp sighting in Amsterdam on a given day, based on 8 verified sightings from GBIF citizen-science data. It is the 138th most-seen of the 234 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.
February
In that month about 20% of wildlife watchers report an Oak Marble Gall Wasp in Amsterdam on a given day, against under 5% in March, May and September–December, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Oak Marble Gall Wasp sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
6th of 16
Of the 16 cities where we can rate Oak Marble Gall Wasp sightings, Amsterdam ranks 6th at about 10%. The best odds are in Liverpool (United Kingdom, about 30%), London (United Kingdom, about 20%) and Birmingham (United Kingdom, about 20%).
GBIF citizen-science records
It is estimated from how often the Oak Marble Gall Wasp is recorded against all the insects logged in Amsterdam (8 verified sightings), 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.
