The insects feed in groups of 5 to over 2000. Tassels, leaves, and silks on which this aphid feeds become black with mold. Leaf deformation, yellowing, and cast aphid skins often are associated with heavy infestations. A silver speckling of the leaves, especially during dry periods, is associated with these pests. In North Carolina, they are usually a problem on corn rather than sorghum.
Severe infestations resemble drought stress since damage progresses from the bottom of the plant up.
Webbing is initiated near the midribs of the host plant and gradually envelopes the plant as the population increases. C. Caterpillars that bore into the whorl, stalk, or ear. All larvae described in this section have three pairs of legs near the head and five pairs of prolegs. When fully grown, this larva is green, reddish, or brown with pale, longitudinal stripes and scattered black spots. Early instars are cream colored or yellowish-green with few markings.