The black cherry aphid is large and shiny metallic black. This pest overwinters as shiny black eggs on twigs and fruit spurs. Eggs hatch shortly before bloom and the aphids can go through a number of generations and may become very abundant in early spring. The population decreases to a very low level on cherry trees during the summer months and primarily survives on mustard family weeds during this period. High populations of the black cherry aphid are mainly a problem on young trees where they cause curling and distortion of the leaves.