Andricus solitarius f. sexual

Small ovoid galls in oak catkins; sparsely hairy, with hairs and remains of antheres at base. A ridge on each side of gall meets at apex. Green-yellow at frst, then brown; exit hole later on in side of gall at tip.

other species form small calls in oak catkins - e.g. Andricus quadrilineatus, Neuroterus politus, etc; see British Plant Galls (Redfern & Shirley 2023) for more details and a key to these rarely recorded galls. 

We recommend that the gall is verified by an expert before submitting to NatureSpot - take good photographs, note the host species and, if possible, retain a specimen

oak trees

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

rarely recorded; probably overlooked