Did you experience a clear sticky substance or black mold on your deck, lawn furniture or car last summer? If so, you may have been experiencing the symptoms of the Asian woolly hackberry aphid, Shivaphis celti. UT’s Insect and Disease Diagnostic Lab first re-ported this aphid in the southern counties of our state in the Summer of 2001. It has since moved into the middle TN area and was re-ported during the summer of 2002.

Hackberry, Celtis occidentalis and sugarberry, Celtis laevigata are the host plants for this aphid. The aphids are small, about 2-2.5 mm long and are conspicuous due to the large amount of bluish white wax secretion from their abdomen. See photo. The adults are winged and give the appearance of small pieces of cotton on the undersides of leaves.

Overwintering eggs hatch into females that, without fertilization, give birth to living fe-males. The ability of females to reproduce without mating is termed parthe-nogenesis. This ability allows young to be brought forth throughout the summer, account-ing for rapid increases in popula-tion. The largest populations usu-ally occur in late July or early Au-gust in our area. In late fall, sexual males and females are born. After mating, the female deposits over-wintering eggs, and the cycle con-tinues the following year.

During severe infestation the aphids excrete large amounts of honeydew, which coats the lower leaves and drips onto objects below the tree. The honeydew attracts ants, bees and other insects and serves as a medium for the growth of sooty mold fungus. In most cases little in-jury occurs to the trees; however, staining of wood, painted surfaces or fabric may occur from prolonged exposure to sooty mold.

Treatment is usually only warranted for trees in areas where staining of decks, lawn furni-ture or other valuable items may occur due to sooty mold colonizing honeydew. Prevention can be obtained by soil treatment or microin-jection from April to mid-June with a sys-temic insecticide such as imidicloprid. Reduc-tion of populations can be obtained by spray-ing small trees with a contact insecticide or microinjection of larger trees in August or September.

Kim Cross