Only few reports have been published on the reduction and recovery of native non-Apis bee populations, measured after temporary or permanent agrochemical pest control in North America. Small species were found to be the most sensitive. The assessment of pesticide toxicity and hazards to non-Apis bees has been practiced for about 50 years through various laboratory, semi-field, and field methods. Studies have been conducted mainly on three species: Nomia melanderi (alkali bee), Megachile rotundata (lucerne leafcutting bee) and Bombus terrestris (bumble bee). Toxicity tests performed in standardized conditions on adults and larvae showed that the intrinsic susceptibility of non-Apis bees measured by oral and topical LD50 or by LC50 varied to a great extent between species and also from Apis mellifera. Laboratory and semi-field tests were used to assess the risks of sprays, field-weathered residues, or systemic compounds in nectar and pollen. The effects of several organophosphates, pyrethroids, neonicotinoids and a carbamate are discussed. Sublethal effects of deltamethrin, fenvalerate, trichlorfon and imidacloprid are also investigated. It has been shown that biochemical data from studies on detoxification in M. rotundata did not agree with toxicological parameters and risk assessment in the field.