Controlled experiments were conducted with two series of ten toads (Bufo terrestris) as caged predators to test the effectiveness of mimicry of the honeybee (Apis mellifera) by the droneflies (Eristalis vinetorum and E. agrorum). A total of 501 flies and 468 bees were offered to the 20 toads, along with 1000 mealworms (Tenebrio molitor) which served as the standard edible insect. It was found that experimental toads which experienced the sting of the honeybee ate significantly fewer droneflies than did the control animals which were not stung by honeybees. Batesian mimicry was shown to be highly effective. Honeybees with their stinging mechanism intact were rejected by the toads to a significantly greater extent than those with it removed, indicating that the sting is the source of noxiousness. When the wings of the honeybees and droneflies were cut off to reduce their buzzing, the experimental toads rejected fewer than when the wings were intact. Therefore audio-mimicry of the buzzing bee as well as visual mimicry of the bee's color-pattern appears to be operating. The data in the present experiments were compared with those from an earlier one and for the first time show that mimetic advantage is proportional to the degree of noxiousness of the model. The more noxious bumblebees conferred greater protection from predation upon the robberflies than the honeybees did upon the droneflies, even though the latter are in fact much better visual mimics.