Aphid infestations can build to severe levels very rapidly because these insects reproduce very quickly. Infestations can be widespread or localized to just a few plants, and they may be worse in some years than in others.
Aphids are soft-bodied and vary in shape and color.
Even a single species may include several colors and shapes. Aphids may or may not have wings. Winged forms tend to develop in response to changes in the environment, such as decreasing daylight or temperature, deterioration of the host plant, or overcrowding. The body of the aphid is segmented, and the head is distinct from the thorax and abdomen. The head bears a pair of segmented antennae and mouthparts for sucking plant juices.