It is the most serious of the five aphid species attacking apple, causing leaf, fruit and systemic root damage. In severe outbreaks, up to 50 percent of the fruit have been injured. When first laid it is a bright yellow, but it gradually changes to greenish-yellow, and finally becomes a shiny jet black. The time required for these color changes varies under normal outdoor conditions from about nine days to more than two weeks.
Winged adults are black and also possess long cornicles and antennae.
Summer generations on plantain look distinctly different from the spring aphids on apple. They are a pale yellowish color, and occur singly or in low numbers, rather than in dense colonies. Plantain leaves are not curled by aphid feeding. Males are scarce and are only found in the fall. Antennae of RAA have six segments, whereas antennae of apple grain aphid have five segments.