Common name: Aphids
Scientific name: Hundreds of species
Hosts: There is a wide range of hosts, depending on the species of aphid. Some species feed on only one host, some alternate between two host species and others feed on a number of hosts.
Aphids are soft-bodied, pear-shaped insects. They are very small, with most species under 1/8 inch in length. Aphids can be almost any color. Some are covered with a threadlike white material, which makes them appear woolly, while others may be covered in a fine dust. There are both winged and wingless individuals of most species.
Aphids can be identified by a beak-like mouthpart (rostrum) that sits far back on the underside of the head. Their antennae are rather long and placed in the front of the head, between the eyes. Aphids have a pair of projections, called cornicles, on each side of their posterior. These structures are reduced in size on some species. The cornicles are used to emit alarm pheromones to warn other aphids of nearby predators.
As individuals, aphids do little harm to a host plant, but large infestations can produce noticeable damage. Their behavior is determined largely by food preference and feeding site. Most are seen on the leaves, stems, and foliage of plants, especially on the new growth, but there are species that feed underground on roots and bulbs. Some produce galls or other deformities.