Sugarcane aphids are distinct from other common aphids in sorghum, in part because the cornicles, antennae and feet all have dark tips. They are often light green to yellowish-whitish-green in color and can be either winged or wingless.
Winged aphids arrive in fields with the aid of wind, and founding adults can be found anywhere on the plant. However, populations usually begin to increase on the undersides of lower leaves in the plant canopy and then rapidly move up the plant as population size increases.
Sugarcane aphids produce large amounts of honeydew, a sticky, sugary substance that coats leaves and reflects sunlight. As populations grow from a single founder event in a field, circles of honeydew-coated plants often develop. With time and the proper environment, honeydew often becomes coated with dark sooty mold and infested leaves appear black.
Alatoid nymphs will soon become winged adults. Photo credit: Patrick Porter.
Typical small sugarcane aphid colony on the underside of a leaf.
Greenbugs are frequently found in large colonies on sorghum as well, but they are easily differentiated from sugarcane aphids because greenbugs have a dark stripe down the back and do not have dark tips on their cornicles.
Photos modified from originals by Rick Grantham, Oklahoma State University.
Two other common aphids on sorghum are shown below.
Patrick Porter, Extension Entomologist