Massalongia rubra is a species of gall midge which forms galls in the leaves of birch. It was first described by the French naturalist and entomologist, Jean-Jacques Kieffer in 1890 and is found in Europe.
An elongate, woody swelling (up to 10 mm long) of the mid-rib of a leaf which can extend into the base of lateral veins and the petiole. The gall is more prominent on the underside of the leaf and is initially green, later red-purple and brown. Sometimes the gall is surrounded by a green island on a yellowing leaf. Each gall contains a single larve which are white or yellowish when young and red when mature, with a weak sternal spatula.[1] Mature larva leave the gall in late summer to hibernate and pupate in the soil. Adults emerge in the following spring or summer.[2]
Affected trees are silver birch (Betula pendula) and downy birch (Betula pubescens).[3]
Massalongia rubra has been recorded from Belgium, Czech Republic, Germany, Great Britain, the Netherlands and Sweden.[3] [4] [5]