Pulsed direct current, square-wave alternating current, alternating current, and direct current, at voltages similar to those currently in use for electrofishing, induced drift by Ameletus dissitus, Baetis spp., Cinygmula par, Hesperoperla pacifica, Psychoglypha subborealis, Hesperophylax occidentalis, and Epeorus longimanus under simulated stream conditions. Of nine species of insects shocked at these voltages, only Simulium jacumbae did not drift. There was an inverse relationship between the propensity of an individual to drift and the minimum level of voltage required to induce drift. Threshold body voltages varied among and within species at different body sizes and at different temperatures. Temporary reductions in productivity with potential loss of species will occur in areas that are electrofished so frequently that rates of insect displacement are greater than rates of insect recolonization.