Aphids as pests

Aphids, or plant lice, are destructive, tiny insects of the order homoptera. They are among the most common insect pests of plants throughout the growing season, and there is hardly a species of plant, cultivated or wild, that escapes aphid infestation.
Aphids are very abundant and diverse in the temperate zone of the northern hemisphere: North America, Europe and eastern Asia are rich in aphid fauna. Aphids are phytophagous (plant eating) insects, which extract vital sap from the leaves and stems of plants. They usually do not kill their host plants, but they frequently reduce plant vigour, distort leaves and cause other malformations.
(E) Emanations of other problems