Late in March, officials of the US Environmental Protection Agency (EPA; Washington, DC) announced that they will review formal requests from Monsanto (St. Louis, MO) to register new varieties of corn and cotton engineered to express new versions of Bacillus thuringiensis (Bt) insecticidal proteins. Monsanto has produced a Cry3Bb Bt corn that targets the coleopteran corn rootworm—the leading target for insecticide use in the US corn belt—setting this variety apart from the now plentiful series of commercial Bt-producing corn lines that target the European corn borer and other lepidopteran pests. Not only is the Cry3Bb Bt corn line considered a different form of insecticide, but its target is a more serious pest (and potentially a larger market) in terms of the damage it can do to commercial corn crops, both as larvae feeding on roots as well as adults feeding on leaves and silks. Monsanto is also asking the EPA to consider an engineered cotton line with two “stacked” Bt-encoding genes to broaden the crop's insect pest resistance. Meanwhile, Mycogen (Indianapolis, IN) and Pioneer Hi-Bred (Des Moines, IA) also have a similar rootworm-resistant Bt corn at an earlier stage of commercial development.