Aphids are the most common insect found on trees, shrubs and ornamental plants and a few species may cause damage but more often this pest is a nuisance as it attracts wasps and can cause a black mold on surfaces around the affected plant. Damage to plants is confined to the leaves as small discolored areas may appear underneath the leaf where theses sucking insects have been feeding although certain species such as the Wooly Aphids will live and feed on the bark. Leaf Curling Aphids will harm the leaf by colonizing and feeding along the leaf edge. As this colony grows the leaves will begin to curl in from the edges with the interior appearing as a white sticky substance from the aphids. General insecticide applications to foliage at timed intervals will control normal aphid populations. For heavy infestations associated with yellow jackets, black mold staining and curling leaves a systemic treatment of Safari 20G is recommended.