The winged morphs are black, although the abdomen can be a different color. The wingless morphs are very variable in color, mostly from yellowish to green, occasionally gray. The wingless adults are 1-2 mm (0.039-0.78 inch) in length.
Initially, leaves will yellow, and with an increasing number of aphids, they will begin to curl. Ongoing infestation can cause stems to become stunted and twisted, especially in cucurbits. Leaves can be damaged to such an extent that they wilt and fall off. The effects of chlorosis and heavy sap loss through sucking severely reduce plant growth and health. The honeydew that forms a sticky film on the leaves after a time, supports sooty mold growth. This impairs photosynthesis, thereby weakening the plant even further, and may render fruits unmarketable.
Like most aphids, A. gossypii is an important virus vector: it can transfer about 70 different types, some of which may cause more damage than the aphid itself.
In temperate regions, A. gossypii is partly holocyclic; but in warmer areas, it will always reproduce asexually. It is unusually resistant to summer heat for an aphid. The generation time can be less than seven days under favorable conditions, and it can produce up to 60 generations per year. With offspring production at more than 70 nymphs per female, the population density may increase very rapidly.