Pea aphids (Acrythosiphon pisum) and an aphid-borne pathogen, pea enation mosaic virus (PEMV), have long worried farmers in the Palouse region of of eastern Washington and northern Idaho, with crop yield loss ranging from 30–40 percent and major outbreaks of pea aphids reported every 6–9 years. (Photo courtesy of Saumik Basu, Ph.D.)