When aphids become overpopulated, they can produce a winged generation that flies off to a new area. Aphids prefer moderate temperatures with a little bit of moisture. Hot summers can retard their growth and damage. When aphids feed, they produce honeydew, a substance that can become so thick it drips from trees and plants onto cars, picnic tables, people and slow-moving pets. Honeydew is just a sugar-water substance and is not toxic to plants or the people it drips on.
Aphids suck and feed on the sap of their host.
If left unchecked, the leaves they feed on begin to curl, providing the little pests a nice protected area where they can continue to feed uninterrupted. Severe infestations cause leaves to yellow and drop. Normally they only weaken the plant, and do not severely damage trees or other woody plants, or cause them to die. The most common and easiest aphid control method is restraint. Be patient and allow natural enemies to come and make a meal of them.