Neuroterus politus is a gall wasp that has two generations per year.

The agamic (asexual) galls are in Oak catkins, usually several per catkin.  They are very small - c.2mm.  Each gall is formed from an anther; the two pollen chambers remain visible as ridges on the gall meeting at the top.  The gall develops in the tissue at the base of and between the two pollen chambers

Neuroterus quercusbaccarum and some Andricus species also form galls in oak catkins.

Under "Species", please select "f. agamic" or "f. sexual" as appropriate. Please provide good close up photographs of the galls -- both in the catkin and removed from the catkin. Also note the host species.

English and Sessile Oak.

In Spring, when the trees are bearing catkins.

The sexual galls form in developing oak buds in about May.

Thought to be quite common in Britain, but not well recorded.

Status in Leicestershire and Rutland not known.

See British Plant Galls (Redfern & Shirley, 2023) and Bladmineerders (Plant Parasites of Europe) webpage