The predatory mitesAmblyseius potentillae, A. cucumerisandTyphlodromus pyrientered diapause in response to a short-day photoperiodic regime, when they were reared on pollen of the ice plant,Dorotheanthus bellidiformis. With pollen of the broad bean,Vicia faba, as food, however, diapause was virtually absent inA. potentillaeandA. cucumerisunder the same short-day regime, but full diapause was found inT. pyri. The importance of carotenoids for the photoperiodic response in these predatory mites is discussed.