Linden aphid

You will find green aphids with black markings clustered on the undersides of linden leaves in late spring through summer. Look for yellowing foliage and honeydew dripping onto surfaces below affected trees. Leaf curling and distortion develop when populations peak. Host trees include American linden, small-leaved linden, and silver linden throughout Western Washington.

Prune lightly infested shoots and avoid excess nitrogen fertilizer, which promotes aphid reproduction. Hose off colonies with water to reduce populations. Encourage natural enemies by avoiding broad-spectrum insecticides. Do not spray when trees are blooming, as linden attracts bees. Dormant oil in late winter suppresses overwintering nymphs if prior infestations were severe.