The corn leaf aphid is a small bluish-green or gray, soft-bodied, spherical insect about the size of a pinhead. The adult females do not lay eggs, as do most other insects, but give birth to living young. These young, called nymphs, resemble the adults except in size. The aphids appear in clusters in the curl of the leaves and upper part of the cornstalk and may completely cover a large area. They are also found in appreciable numbers down in the whorl and on the unemerged tassel. Most of the aphids in a cluster are wingless. However, when clusters become large, females with delicate, filmy wings appear. The wings enable them to fly to other uninfested plants and start a new colony.