The corn leaf aphid (CLA), Rhopalosiphum maidis (Fitch), is found on field corn in the midwest Cnited States each year. Except for infrequent and scattered outbreaks, CLA populations remain at low levels. Injury to corn occurs during tasseling (Snelling et aL 1941) and is caused by CLAs which are the progeny of colonizers that arrived 2-3 weeks earlier when the corn was in the whorl stage (Bryson 1934, Falter 1963).
Wagner, S. W. and Ruesink, W. G.
"The Distribution of Natural Enemies of the Corn Leaf Aphid (Homoptera: Aphdidae) on Field Corn,"
The Great Lakes Entomologist, vol 15
Available at: https://scholar.valpo.edu/tgle/vol15/iss3/2