Every bright monarch butterfly or striking luna moth started out in a far subtler form of nature’s mosaic, a humble caterpillar. It is this early stage of life—crafted by natural selection into machines for converting a vast array of plant matter, mostly leaves, into the beautiful adults that have captivated humans for millennia—that this book brings to dazzling light. Unobtrusive as they go about their business, these caterpillars are rarely seen by humans—and are virtually never seen from the perspective presented in this sumptuous volume: photographed in extreme close-ups at a resolution that captures in sharp detail the exquisite colors and features eluding the casual observer. Gathered by biologists Daniel Janzen, Winifred Hallwachs, and Jeffrey Miller in the tropical dry forests, cloud forests, and rain forests of northwestern Costa Rica, over 100 large-format photographs of caterpillars document the dizzying variety of shapes, vivid colors, and cryptic markings among these species. The pictures are accompanied by capsule species accounts—revealing life histories as diverse as their forms—and magnificent images of the adult butterfly or moth. Throughout, the authors convey an intimate sense of these creatures—studied over twenty-five years—by focusing on how their features figure in their behavior and ecology, and on the beauty of nature in this life stage, as well as the nature of that beauty. The story of the caterpillars is also the success story of Area de Conservacion Guanacaste—where the long-term work of Janzen and Hallwachs, and a team of gusaneros (caterpillar collectors and rearers), along with the participation of neighboring farming communities, has deepened understanding of Costa Rica’s Lepidoptera and has brought about advances in restoration ecology of tropical habitats, biodiversity prospecting, biological control of pests, biotechnology, residents’ bioliteracy, and ecotourism development.