The larvae of the gall midge Anisostephus betulinus cause galls to form on the leaves of Birch (Betula species). The galls take the form of a deep, circular blister about 3 mm across, 1.5 mm deep, yellowish to red-purple in colour, in the leaf blade or over veins and more prominent on the upper surface.

There are similar galls on Birch, and reference to the key in Redfern and Shirley (2011) is recommended.  Identification may be confirmed by close examination of the lava inside the gall. 

Gall Adult

Wherever the host Birch species occur.

When Birch is in leaf.

The larvae leave the galls from July to September.

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

Status in Leicestershire and Rutland not known.