A REVIEW OF FALSE HEADS IN LYCAENID BUTTERFLIES

Butterflies and moths (Lepidoptera) are known for having an array of antipredator defenses associated with their wing patterns and color, and they have long been considered model organisms for studies on animal mimicry. One of the most fascinating examples of mimicry in the animal kingdom is that of `false heads' - structures that resemble cranial attributes. False heads are predominantly found in the butterfly family Lycaenidae, especially the hairstreak subfamily Theclinae where the false head is found at the posterior margin of the hindwing. These heads are believed to deflect predators to less vulnerable regions of their bodies. False heads are accompanied by a variety of behaviors that may enhance survival, such as walking in a circular pattern and moving hindwings along the sagittal plane. At least five different hypotheses have been proposed to explain why butterflies have evolved false heads in response to predation by visual predators, which we name, summarize, illustrate, and discuss. Our review reveals gaps in our understanding of false head evolution, especially because few experimental studies have tested these hypotheses with appropriate predators. We discuss strengths and weaknesses of each hypothesis and propose avenues for future experimentation. In particular, exploring hypotheses using comparative evolutionary and ecological studies will provide greater understanding of the adaptive significance of these anti-predator structures and behaviors.