Do courtship flashes of fireflies (Coleoptera: Lampyridae) serve as aposematic signals to insectivorous bats?

Adult males of some species of fireflies (Coleoptera: Lampyridae) are chemically defended and produce bioluminescent courtship signals while flying in search of females. These signals may have positive or negative consequences unrelated to mating. Eavesdropping Photuris fireflies use bioluminescence to locate and prey on smaller Photinus. We examined whether flash signals of Photinus act as aposematic signals against insectivorous bats. We used field observations of four species of North American bats, diet and controlled behavioural experiments to assess taste aversion and responses to simulated fireflies. Fireflies were absent from the bats' diet even though these species co-occurred at our field sites and bats consumed other coleopterans and firefly-sized prey. Caged bats rejected mealworms coated with homogenized fireflies, and flying bats responded differentially to moving lures based on a combination of flash cues and lure size. Flash signals of fireflies probably operate as aposematic warnings to the common bat, Eptesicus fuscus, supporting the idea that bioluminescent courtship in fireflies operates under competing selective pressures.