The courtship of butterflies begins with a general attraction of males to moving objects. If the object of the attraction is a receptive female, her response wil1 elicit further courtship behavior from the male. Male courtship pheromones are disseminated during the aerial phases of courtship and after the female has landed. While female butterflies generally lack specific courtship pheromone glands, females of some groups do possess these. Courtship pheromones of males of four members of the subfamily Danainae in the family Nymphalidae have now been identified. Three of these share the same active component, but each has specific additional components. Although the courtship pheromone secretions of butterflies have odors which are very distinctive to humans, the active compound of these pheromones is odorless to humans and elicits responses from antennal receptors of all butterflies tested. The pheromone receptors are short thin-walled pegs on the antennae of both male and female butterflies.