Harmandiola tremulae is a gall midge whose larvae feed on Aspen causing galls to form on the upperside of the leaves. The galls are globose, 3 to 4 mm across with thick walls, glossy-red when mature but often turning black later.  The opening to the gall is underside, and surrounded by a slightly protruding rim.

Several other species cause spherical galls on Aspen.

Gall  Adult

On Aspen (Populus tremulae).

The larval stage is from June to September.

The larva is orange-red.

Widespread, though little recorded in Britain. 

Thought to be fairly frequent in Leicestershire and Rutland.