Adults range from Mexico through Panama. G. oto visits common flowers like lantana, but prefers to lay its eggs on plants of the tropical nightshade genus Cestrum. The red and purple striped caterpillars feed on these toxic plants and store the alkaloids in their tissues, making them distasteful to predators such as birds. They retain their toxicity in adulthood. The same alkaloids that make them poisonous also are converted into pheromones by the males, which use them to attract females.