(Brachycaudus persicae)
Myzus persicae, known as the green peach aphid, greenfly, or the peach-potato aphid, is a small green aphid belonging to the order Hemiptera. It is the most significant aphid pest of peach trees, causing decreased growth, shrivelling of the leaves and the death of various tissues. It also acts as a vector for the transport of plant viruses such as cucumber mosaic virus (CMV), potato virus Y (PVY) and tobacco etch virus (TEV). Potato virus Y and potato leafroll virus can be passed to members of the nightshade/potato family (Solanaceae), and various mosaic viruses to many other food crops. Originally described by Swiss entomologist Johann Heinrich Sulzer in 1776, its specific name is derived from the Latin genitive persicae "of the peach". The green peach aphid is found worldwide but is less tolerant of colder climates. It overwinters as an egg, laid in trees of the genus Prunus. The aphid can benefit from the presence of greenhouses in these areas. Adult green peach aphids appear in the summer, and are 1.8 to 2.1 mm long; the head and thorax are black, and the abdomen yellow-green with a dark patch on the back. The nymphs are at first greenish, then yellowish in color; those that become winged females may be pinkish. Wingless adults resemble nymphs and are 1.7 to 2.0 mm long. The green peach aphid can be yellowish-green, red, or brown in color because of morphological differences influenced primarily by the host plants, nutrition, and temperature. In the warmer months, and throughout the year in warmer climates, the green peach aphid reproduces asexually; adults produce nymphs on a wide variety of herbaceous plant material, including many vegetable crops such as cabbage and its Brassica relatives, potato and other crops of the family Solanaceae, celery, mustard, pepper, pumpkin, okra, corn, and sunflower and other flower crops. Herbaceous weeds, such as white goosefoot (Chenopodium album) and common tumbleweed (Amaranthus retroflexus) in the United States, also act as hosts. An individual can reproduce 12 days after being born and up to 20 generations may occur over the course of a year in warmer areas. As the weather cools, aphids mate and lay their tiny (0.6 mm x 0.3 mm) oval eggs in crevices of the bark of Prunus trees. The green peach aphid is an agricultural pest across the United States and worldwide, including Australia. Although insecticides are used to control it, it develops resistance.