Aphid colonies may be found on young leaves, new succulent shoots, and twigs or branches. Many vegetables and fruit trees, as well as ornamental plants, are attacked. This species is the green apple aphid. Aphid feeding often causes leaves to curl and become deformed. Once this happens, control is very difficult because aphids inside the curled leaves are protected from contact with the insecticide.
Some aphids are important vectors of plant diseases.
Aphids excrete a sugary waste produce called honeydew. Notice the clear drop on the left side of this picture. Ants, bees, and wasps collect honeydew for food. Black and brown fungi, appropriately called sooty molds, cover leaves and other objects below aphid colonies where honeydew collects. Sooty mold problems can be prevented by controlling the resident aphids.