They can usually be recognized by the pear-shaped body and fairly long antennae. There are both winged and wingless aphids in most species.
Honeydew consists mainly of excess sap ingested by the insect and passed through the body.
Aphids may damage many plants including fruits, vegetables and ornamental trees and shrubs. The major damage is caused by the aphids sucking the juices from the stems and leaves causing a reduction in vigor, curling and distortion, and reduction in yield. Some species inject saliva into the plant tissue as they feed and may transmit virus diseases from one plant to another. In addition to the direct damage caused to the plant by the aphids feeding a black fungus, known as sooty mold, grows on the honeydew secreted by the aphids. Sooty mold is unsightly and in association with honeydew it is objectionable to the buyer of affected plant material, fruits or vegetables.