[2] The spangle gall generation on the underside of the oak leaves are flat discs, with a distinct central elevation, slightly hairy, yellow-green at first and reddish later, attached by a short stalk.

These galls are up to 6 mm in diameter, unilocular, unilarval with a whitish or yellow undersurface; they mature in September, detach and fall to the ground before the leaves themselves.

[3] The smooth surfaced currant gall generation appears in April and lay unfertilised eggs in the staminate catkins or occasionally the developing young leaves.

The resulting spherical galls are around 4 mm in diameter, unilocular and unilarval, green at first, maturing through pink to red, therefore closely resembling redcurrants.

[8] The male and female of the bisexual generation emerge in June from the currant galls and after mating the fertilised eggs are laid in the lower epidermis of the oak leaves.