These small, delicate, louse-like sucking insects often are found on sugar maple foliage. Their populations may be dense enough for feeding to stunt foliage and cause it to wrinkle and discolor. Foliage may turn brown to nearly black in heavy infestations. Damaged foliage may also drop prematurely. Aphids excrete large amounts of honeydew, a concentrated mixture of sugar and water that is removed from the tree during feeding. This sticky substance often coats foliage and bark (giving a glazed appearance) or even vehicles parked beneath heavily infested trees.

Recently, large numbers of aphids have been noted on sugar maple in New England during spring and early summer. The most common species is closely related to the Norway maple aphid. The earliest stages to appear in the spring are purplish-brown to brown nymphs and wingless adults. At first they infest buds, but later they form colonies on the underside of expanding foliage (Fig. 55). They also infest petioles and green shoots and tend to cluster at the junction of the leaf and petiole. Winged adults are dark brown (nearly black) and slightly less than 0.12 inch (3 mm) long. They first appear in early summer. These aphids are unusual in that they spend most of the summer in a resting stage (or a dimorph). The immobile dimorphs are less than 0.12 inch (3 mm) long, whitish and translucent, and are flattened against the undersurface of the leaves.