Andricus grossulariae

Andricus grossulariae is a gall wasp that causes two types of gall to be formed on Oak (see Life History). It is a member of the Cynipidae family together with many other gall-causing wasps.

Andricus quercuscalicis forms similar asexual galls on acorn cups, but with a single larval chamber in inner gall.

Sexual galls are formed on Turkey oak catkins by Andricus quercuscalicis; these are much smaller and are green at first, then pale brown 

Agamic/sexual galls  Adult

State host and provide photo

Around the host Oak trees.

See Life History.

Andricus grossulariae causes two types of gall to be formed on two species of Oak.

In spring, galls are caused by the sexual generation of wasps on the catkins of Turkey Oak . These galls only grow to about 6mm and shaped like pointed peas; green at first, then becoming bright red.  The vacated brown galls often persist into autumn. 

In late summer and autumn, large asexual galls are formed on the buds, catkins or acorn cups of Pedunculate Oak and Sessile Oak. In both cases the galls first appear pink in colour and as they mature they turn red, then green and finally brown.

Arrived in Britain around the year 2000 and now spreading northwards.

Only recently arrived in Leicestershire and Rutland.