Oyster Gall

Neuroterus anthracinus

The asexual generation of the gall wasp Neuroterus anthracinus leads to the formation of small, egg-shaped galls approximately 3mm in diameter on the midrib of oak leaves. Each gall has a small flap of tissue protruding from each side of the base, which is a key feature for identification to differentiate it from similar species. The galls start as cream or green in colour, develop reddish-brown spots before maturing, and eventually fall from the leaves in autumn. Adult wasps emerge in winter and spring to lay eggs in buds, which will develop into the sexual generation. Also found on Sessile Oak.