Galled redcurrant (Ribes rubrum) leaf. The underside of a redcurrant leaf that has been colonised by the redcurrant blister aphid (Cryptomyzis ribis). The blistered area of the leaf has developed a red pigmentation, and also surface hairs. The many wingless aphids (aptera) visible developed parthenogenetically from overwintering eggs laid on the plant in the previous Autumn. This picture was taken in early June, in 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.