The matador bug’s elaborate flags deter avian predators

Large, conspicuous traits frequently evolve despite increased predator attention, but in some cases, specifically to attract attention. Sexually selected traits provide some of the clearest examples of elaboration, yet natural selection can also be a powerful driver. The matador bug, Anisoscelis alipes (Hemiptera: Coreidae), has large, colorful flags on its legs that, unlike many other coreid species, are not used in reproductive competition. We hypothesized that these flags either a) warn predators of chemical defense, or b) deflect predatory attack to the removable hindlegs. We pitted matador bugs with or without flags and crickets (Acheta domesticus) with or without bug flags experimentally attached to their legs, against live motmot bird predators (Momotus subrufescens and Electron platyrhynchum). Contrary to the deflection hypothesis, almost none of the predatory strikes were directed at hindleg flags. Instead, we found support for the aposematism hypothesis: matador bug flags reduced attacks on palatable crickets, but were unnecessary to prevent predator attack against matador bugs. Palatability studies with naïve chicks (Gallus gallus) further supported a chemical defense hypothesis. Thus, these elaborate hindleg flags serve an aposematic anti-predator function, but in their absence, birds use alternative cues. These findings add to our understanding of the role of predation in driving the evolution of elaborate morphological structures.