Solitary bees provide essential pollination services. Concerns for the decline of these wild bee species have led to calls for their inclusion in pesticide risk assessment. Solitary bees differ from honey bees in their physiology and ecology and this may affect how they respond to pesticide exposure. Here we investigate the life-time toxicity of two insecticides, the organophosphate dimethoate and neonicotinoid clothianidin, for two mason bee species, Osmia bicornis and O. cornuta using a toxicokinetic/toxicodynamic stochastic death model taken from Dynamic Energy Budget (DEBtox) theory. Both species showed concentration and exposure duration dependent effects for each chemical. LC