Schizaphis graminum These small aphids usually overwinter in the South and are carried into northern states by the wind. Sometimes they also overwinter as far north as Ohio, however. They can build up to damaging numbers very quickly. They are about 1/16 inch long and pale yellow to green with black eyes. Like other aphids, they feed by sucking sap from grass blades. Greenbugs inject a toxin as they feed, doing more damage than just removing sap. Their damage is first visible as pale areas streaked with yellow. Later, the blade turns a characteristic tan-to-orange color. Damage usually starts in a shady spot, but can also occur in full sun. Bluegrass is a favored host. Greenbugs have long been a pest of wheat and oats in the Midwest, but just recently, in the 1970s, began to feed on bluegrass.
Greenbugs are not difficult to control, but can do a great deal of damage if left uncontrolled.