Redcurrant blister aphid

The blisters on the leaves start out yellow in spring and turn red by early summer.

The aphids hide under the leaves, inside the hairy dents made by the blisters.

In summer some aphids fly off to another plant, while others stay on the currants.

In autumn the females lay eggs on currant twigs, and the eggs hatch the next spring.

It can also live on blackcurrants and gooseberries.