The larvae of the gall midge Semudobia tarda cause galls to form in the catkins of Birch (Betula species).  The gall is in the fruit, and is rounded, c. 2,, diameter, with a polished surface and hairs only at apex; the wings of the fruit are almost completely absent.    The 'window-pit' is absent or indistinct on this gall - compare S betulae.

Semudobia betulae and Semudobia skuhravae also form small galls in birch catkins

Gall Adult

Tease the catkins apart to see the galls - it helps to do this under a microscope

Close photos of the gall in the fruit

Where the host trees occur.

When Betula seeds are present in mature catkins in summer; old galls may also be found in previous year's catkins retained on the tree over winter. 

It is difficult to determine the status in Britain due to lack of records.

Status in Leicestershire and Rutland not known.