Aphids may be wingless or may have functional wings. The offspring are smaller than the adults and are always wingless. While feeding, aphids inject saliva into the plant. The saliva of some aphids causes curled or distorted growth. Some aphids transmit plant viruses as well.
Aphids excrete a sweet, sticky liquid called honeydew.
When aphid numbers are large, honeydew often completely coats leaves and other object below, giving infested plants a sticky or varnished appearance. Honeydew attracts ants, flies, wasps and other insects. Unsightly fungi called sooty molds often develop in honeydew, further disfiguring plants. The young aphids mature in about 10 days. Most aphids species have several generation per year.