Aphids also have been shown to transmit more plant diseases than any other type of insect. While aphids can be many colors, the most common are yellow or light green. They also can be black, shades of red, brown, white, or grey. Some might even be covered with a white cottony material. Most aphids are wingless, but colonies may have both winged and wingless forms.
Aphids have thin legs and long, thin antennae.
When aphids occur in small numbers, this feeding activity doesn't hurt plants. But aphid populations can build up quickly, and when this happens, damage to the plant can occur. The result is wilting and yellowing, which can cause leaves to curl, leading eventually to the plant's death. Where massive aphid populations are feeding, the plant leaves may turn black. Sometimes honeydew from aphids falls like a fine rain, landing on lower plant leaves or small plants growing below taller plants, where it dries in a clear, shiny drop.