Laboratory bioassays with green peach aphids, Myzus persicae (Sulzer), were conducted on samples from field grown spinach and mustard greens to determine the persistence of triazamate, dimethoate, and mevinphos. Treatment with each insecticide resulted in similar mortality initially on both crops. Mortality on samples from mevinphos treated plants declined considerably by 1 d after treatment. Dimethoate persisted for > 4 d at a level that would kill at least some aphids during the allotted time. Persistence of triazamate and dimethoate activities were similar on spinach. Triazamate, however, resulted in greater aphid mortality through time on mustard greens than did dimethoate.