The larvae of the gall wasp Andricus callidoma cause galls to form on Oak.

The asexual gall emerges from an unopened bud. The stalk is 3 to 5 mm long and can be much longer, the gall itself is approximately 2 x 4 mm with a pointed tip.

The sexual gall is on oak catkins, and forms a ball c.5mm wide of white cottonwool-like hairs.

Andricus malpighii casuses very similar asexual galls, and the adults may need to be bred from the gall to identify.

Gall  Adult

Where Oak (the host species) is present.

May to September.

Uncommon and little recorded in Britain.

Uncommon in Leicestershire and Rutland.