Galled redcurrant (Ribes rubrum) leaf. The underside of a redcurrant leaf that has been colonised by the redcurrant blister aphid (Cryptomyzis ribis). The blistered areas of the leaf develop a red pigmentation and short surface hairs in response to the presence of the insects. The many wingless aphids (aptera) visible developed from overwintering eggs laid on the plant in the previous Autumn. This picture was taken in June in the UK. Blister galls are a familiar sight on redcurrant bushes in gardens. They occur at the tips of growing branches and cause little loss of the crop. In summer, the aphids produce winged forms (alates) that migrate to other plants, such as hedge woundwort. In autumn, they return to the currant bushes to lay their eggs, which overwinter, completing the cycle.