When thinking on butterflies, it is not common to think on cruel carnivorous killers. Actually, of the four mega-diverse insect orders, only Lepidoptera are almost exclusively phytophagous and less than 1% of Lepidoptera, or as few as 200 to 300 species, have been recorded as "aphytophagous", feeding on anything other than living plants. Some aphytophagous Lepidoptera are predators that eat other animals, primarily insects, others are parasites, which lower their host's fitness without killing them, and some taxa feed on detritus, lichen, and extrafloral nectar. Despite multiple shifts away from herbivory within the Lepidoptera, aphytophagous lepidopteran lineages rarely persist and radiate.

However, the lycaenid subfamily Miletinae are a conspicuous exception to this general pattern and is the largest radiation among aphytophagous butterflies, consisting on nearly 140 species. The larvae of most miletines are Hemiptera predators, and some are ant parasites. In this study, a well resolved phylogeny is used to discuss the evolution of aphytophagy, shifts in diet breadth and preferences, and ant associations with hemipteran prey. In addition, researchers examine the biogeographic history of the group and discuss the causes and effects of dramatic dietary shifts between different trophic levels.

Reference Article: Zofia A. Kaliszewska, David J. Lohman, Kathrin Sommer, Glenn Adelson, Douglas B. Rand, John Mathew, Gerard Talavera and Naomi E. Pierce. 2015. When caterpillars attack: biogeography and life history evolution of the Miletinae (Lepidoptera: Lycaenidae). Evolution. DOI: 10.1111/evo.12599