Both males and females are wingless, have no mouthparts and do not grown after birth. A few days after mating, the female lays a single long, dark, oval, cinnamon-colored egg almost as large as her body in a crevice of the bark. These winter eggs hatch in early spring into wingless aphids. Because of the virtual disappearance of American elm trees, the woolly apple aphid most often lives on apple trees throughout the year. Each group of aphids, small or large, is considered a colony.
Aphids are present more nearly year round on the roots than on the tops.
The aerial forms are most commonly found on the twigs, water sprouts and callus tissue in wounds, cankers and scars. Wingless females in the aerial colonies may give birth to nymphs at any times in spring, summer or fall. Newborn nymphs are very important in the spread of the woolly apple aphid. They spread either through some mechanical agency or directly by crawling. Birds and insects can also transport aphids.