Scanning electron microscope image of the hindwing of a male Heliconius butterfly shows brush-like structures on the specialized androconial scales (A; magnified in D). The male forewing (B) and the female hindwing (C) lack these brushes.SOHINI VANJARI / BUTTERFLY GENETICS GROUP / UNIVERSITY OF CAMBRIDGE Pheromones are known to play an important role in the courtship of various butterfly species. Taking a deep dive into the pheromones of Heliconius melpomene, researchers have identified specialized brush-like “scent” scales—known as androconia—on male hindwings. These structures are involved in the release of pheromones. A follow-up series of experiments demonstrated the importance of this chemical signaling: females are less likely to mate with males if their androconial region has been experimentally blocked.
K. Darragh et al., “Male sex pheromone components in Heliconius butterflies released by the androconia affect female choice,” PeerJ, doi:10.7717/peerj.3953, 2017.