Great bark aphids (Longistigma caryae) on an immature pecan
(Carya illinoensis 'Sumner').
Photo by J.S. Corser, Durham Co. Master Gardener.
Aphids are small, soft-bodied, pear-shaped insects that measure 1/16 to 3/8 inch. There are several species of aphids. Depending on species, they can range in color from tan, pink, or green to almost black and may or may not have wings. Aphids feed on leaves and stems by piercing the plant tissue and sucking plant sap. Their feeding can cause leaves to curl or become distorted. In addition, aphids sometimes serve as vectors to transmit plant viruses which may result in disease development. The first sign of aphids being present is usually a sticky residue left on leaves. The aphids excrete a sticky substance called honeydew as they feed. The honeydew will land on any surface beneath the feeding area, such as leaves, branches, understory plants or even cars and concrete surfaces. Sooty mold is a fungus that grows on the sticky surface of the honeydew. As the sooty mold grows it will form a black, powdery or velvety coating on leaves and other areas where the honeydew landed. The good news is that sooty mold does not infect the plant tissue.
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