It is rare for people to take the time to look at the small and plain things that live around us but for those that do there are exciting discoveries that can be made as has been the case for local naturalist and recorder Susan Marley.
A photo added to iNaturalist of a rather non-descript gall she encountered on an Oak tree was confirmed as a species of tiny gall-forming wasp, Andricus infectorius, this is just the second time this species has been recorded and reported in Merseyside and the first time the species has made it into the UK recording network for Lancashire and at the time of writing only the 5th known record for the UK as a whole. No records currently exist on the NBN Atlas with just two in the UK on iNaturalist and just three on iRecord (including Susan’s)
Susan discovered the gall at Eaton Street Park, Prescot, Merseyside, on 05/08/2022, Grid Ref SJ46689319. The record identification was confirmed by photo first on iNaturalist by Giusy Roera then verified by Chris Leach of the British Plant Gall Society.
An earlier observation on iNaturalist from 1st September 2020 is present but the identification has not yet been confirmed. This sighting by Brenda Cameron, if confirmed, would be the first for the area.
There are several Andricus species and for the most part they can be identified through the presence of the gall that they form on their host tree. Andricus kollari, the Oak Marble Gall Wasp, is the most widely observed species in North Merseyside and forms (as the name suggests) a near perfectly round, smooth ball attached to it’s host Oak.
Other species known to be present in the area include Andricus quercuscalicis (Knopper Gall Wasp), Andricus lignicola (Cola Nut Gall Wasp) and Andricus foecundatrix (Oak Artichoke Gall Wasp) each of which resembles to some extent its name-sake.
Help to improve our knowledge!
These Andricus species can be readily identified from the presence of their galls. A photo is enough to confirm their presence and they often occur low down on Oak trees making them quite accessible. Yet for most species we know little about their distribution in our area and this is where we need your help.
Why not get involved, visit a park local to you (or further afield if you’re feeling adventurous!) and take photos of any gall you find. Even if you don’t know the species, upload it to iNaturalist and let the community help you with the identification. There is even a ‘Gall Week‘ coming up where people all around the world will be hunting and reporting sightings of galls. More information on that here: https://www.inaturalist.org/posts/68856-gall-week-2022-new-project
