Contact toxicities were established for acetone formulations of azinphosmethyl, carbaryl, methyl parathion, and permethrin applied to workers of Africanized and European honey bee (Apis mellifera L.) types. For each insecticide, 95% fiducial limits at the LC50 levels for the two bee types did not overlap. Africanized bees showed greater tolerance to all the chemicals except carbaryl; differences in tolerance to each of the four chemicals were all about 2-fold. The order of toxicity of the compounds on the Africanized bees was permethrin > carbaryl > azinphosmethyl > methyl parathion; on the European honey bees, the order of toxicity was permethrin > azinphosmethyl > carbaryl> methyl parathion. Significant differences between the bee types were noted in the slopes of the probit regressions estimated for three of the compounds. The Africanized bees responded more homogeneously than the European bees to azinphosmethyl; European bees reacted more homogeneously than Africanized bees to carbaryl and permethrin.