The tribe Eumolpini is the largest group of leaf beetles in the subfamily Eumolpinae, encompassing around 170 genera worldwide. Known for their rounded shapes, metallic colors, and specialized body grooves that mechanically lock their hard wing covers (elytra) shut against predators, these beetles carry an ancient lineage. DNA and fossil studies trace some South Pacific groups back to the Cretaceous-Paleogene extinction event that wiped out the dinosaurs. While the adult beetles feed above ground on leaves, flowers, and fruit, their underground larvae chew on plant roots. Many species specialize in eating toxic plants, sequestering those chemicals in their bodies to make themselves unpalatable to predators. In tropical regions, adult beetles often emerge from the soil in massive swarms immediately following the first heavy summer rains. I spotted this super-cute specimen in Yasuní National Park, a breathtaking haven of the Ecuadorian Amazon. Given the overwhelming diversity of this ancient tribe, identifying the exact species from a photograph alone is a massive challenge!