This is the largest aphid species occurring in the United States, and is found throughout the U.S. from north to south and east to western states. It infests a variety of hardwood trees, including oak, hickory, sycamore, willow, walnut, and pecan. Large populations can produce copious quantities of honeydew that drip onto surfaces below as well as sustain the growth of sooty mold. Their feeding can reduce the vigor and health of a tree, but whether or not they actually cause the death of trees is unknown. These aphids can be present on susceptible trees from mid-spring to the end of summer, although in the dry, arid southwestern states the heat of mid-summer may cause populations to go dormant.
Control for the sake of the tree may not be needed, but to reduce the copious amounts of dripping honeydew over vehicles or locations of human activity a control program may be needed. A foliar spray with a labeled product can be applied to the leaves, branches, and possibly the trunk of infested trees. A soil application with a systemic done in late winter will provide good control of aphids feeding on the foliage.