Circadian and seasonal changes in the susceptibility of honeybee (Apis mellifera) workers to intoxica- tion by organophosphate, benzoylphenyl urea, carbamate, and oxadiazine insecticides have been studied from 2008 to 2009. Animals were collected in two apiaries located in the surroundings of Mielec and Tarnobrzeg in the Sub-Carpathian Province. The experiments consisted of intoxication by select xenobiotics of the subse- quent groups of animals in two-hour intervals for a period of 24 hours and the analysis of their survivability. Experiments were carried out in spring and summer. The results suggest that the susceptibility of bees to dif- ferent groups of insecticides varies significantly, both in the circadian and seasonal rhythms.