currant blister aphids, cryptomyzus ribis, feeding on the underside of a redcurrant leaf

leaf plant flower green produce nature tree frost food branch shrub wildflower herb water blossom grass autumn currant blister aphids cryptomyzus ribis feeding underside redcurrant farming red aphid colonies ribes rubrum agriculture parasitic isolated natural illness close problem spring sick sickness spot damage macro disease parasite closeup bush summer agricultural leaves insect infected gallic garden upper side warts broken pest gall close-up leaf