The pea aphid has a worldwide distribution. It is light-green with unusually long legs and cornicles (tail pipe-like projections). It is the primary aphid that attacks peas, and is also a pest of fava beans, and lentils.
Life Cycle: This aphid overwinters as an egg on alfalfa, vetch, and clover, where the population will reproduce and build up in the spring. They will move to peas after the plants emerge in the spring. Live females nymphs (no egg stage necessary) are produced throughout most of the year. Females take 12 days to mature and produce up to 150 nymphs. There are between 13-20 generations per year. Adults may or may not have wings, but will produce winged individuals and disperse if conditions become crowded or plants become desiccated. Sexual forms will occur in the fall and eggs will be laid after mating. Populations tend to be lower after cold, snowless winters or springs with persistent wet weather.
Damage: Infestations during the bloom and early pod stages will reduce yield and crop quality by removing plant sap, impairing pod appearance, reducing seed fill and by the presence of aphid honey-dew. Plants with high populations also have a reduced ability to fix nitrogen. Pea aphids can transmit many different viruses, even to crops that they rarely feed on, such as cucurbits.
Monitoring: Start monitoring when plants begin to flower. Action threshold include, 1-2 aphids per leaf, 2-3 aphids per stem tip or 9-13 per sweep, if a sweep net is being used.
Cultural, Biological and Chemical Management: Harvest or spray nearby alfalfa, vetch or clover before winged adults are formed in the spring. Varieties differ in their susceptibility to pea aphid damage. Plant varieties less prone to high infestations and damage. There are many natural enemies (lady beetles, lacewings, flower fly larvae, predatory midges, Braconid wasps) that help reduce aphid numbers, but they may not provide adequate control. Fungi will control high aphid populations during warm, humid or wet weather. A single systemic insecticide application (i.e. dimethoate) will control this pest. There are also many other products registered for use on pea aphids (see New England Vegetable Management Guide).
T. Jude Boucher, University of Connecticut, Cooperative Extension System
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