The gall wasp causes scaly, marble-like agamic galls to form in the leaf axil buds and terminal buds of English Oak and Sessile Oak.They are smaller than Andricus kollari Marble galls, and are rougher/lumpier in appearance, grey-brown in colour and very hard, persisting for several years.  They are usually found in small clusters.

[Note: Sexual galls are formed in the buds of Turkey Oak, but are difficut to separate from the sexual galls of A kollari and A corruptrix).

Andricis kollari and Andricus infectorius

Photograph the gall on oak, and note the host species

Native oak trees

Very common (British Plant Galls, Redfern & Shirley, 2023)

common

See British Plant Galls (Redfern & Shirley, 2023)