Puddling in butterflies: current knowledge and new directions

Abstract Puddling, a behavior in which butterflies and other insects aggregate on mineral-rich substrates such as mud, animal excrement, carrion, and even human perspiration, is a well-documented phenomenon in both temperate and tropical regions. This behavior is thought to compensate for the limited access to micronutrients in the adult diet that are important for fitness, primarily sodium and nitrogen, essential for nervous system function, growth, and reproductive processes. In this review, we consolidate existing knowledge on butterfly puddling and highlight key gaps in our understanding. The review is organized into 4 main themes: the benefits of puddling, social dynamics in puddling, sensory cues for site selection, and behavioral variation across species and regions. We explore how nutrient preferences are influenced by diet, environmental factors, and evolutionary history, with a particular focus on the role of sodium and nitrogen. We also discuss the potential reproductive benefits of puddling, including its impact on mating success and fecundity. In addition, we consider the sensory and social mechanisms butterflies use to locate suitable puddling sites. Lastly, we give a short overview on puddling in moths. This review identifies several areas for future research, particularly in understanding the adaptive significance of puddling across different taxa and environments.