The larva of the gall midge Massalongia rubra galls the leaves of Birch (Betula). The gall takes the form of an elongated woody swelling along the midrib of a normally expanded leaf. The gall may be up to 10 mm in length. It may also affect the petiole or extend into the bases of lateral veins. It is most prominent on the underside of leaves and starts of green in colour becoming red-purple and then brown.

Gall Adult

Where Birch is present.

Galls can be seen when Birch is in leaf.

The midge larvae are white or yellowish when young red when mature.

Not well recorded but seems to be quite widespread in England and Wales.

Status in Leicestershire and Rutland not known.