During courtship, males and females Tree Nymphs fly together for long periods, and the male extends two brush-like organs (known as hair pencils) from the tip of his abdomen. These hair pencils brush against the female’s antennae and release pheromones and other chemicals that stimulate her to mate. One of these chemicals, danaidone, is poisonous, and is also passed to the female with the sperm during mating. (This substance is gathered by the adult males from various plants and deters predators from eating the butterflies.) Some of the danaidone passed to the female from the male during mating ends up in the tissues of the female and in her eggs, protecting both the female and the eggs from predation.