Similar dual-function traits can be found in male deer and other ungulates, which use their antlers for fighting off rivals and signaling their vigor to females. Many structures in the animal and plant kingdoms have dual functions, such as the vivid colors of strawberry poison dart frogs (Oophaga pumilio), which both deter predators and help males attract mates. Yet, silkmoth tails are not simply utilitarian decoys for bats they are often visually stunning, akin to decorative streamers trailing behind a kite. The longer the tail, the more likely the moth is to successfully evade a hunting bat. Silkmoth tails, for instance, have evolved independently across three continents and vary significantly in length.

This phenomenon, where traits evolve for one specific function and are then co-opted by natural selection for another, is not uncommon in nature. Rubin’s curiosity led her to question whether the twisted tails of Luna moths could serve additional purposes or come with hidden costs. From experimental work with bats and moths in a flight room, we’ve found that these structures seem to reflect bat sonar in such a way that bats often aim their attacks at the tails instead of the main body.”

Juliette Rubin, a doctoral student at the Florida Museum of Natural History and lead author of both studies, described the structure of Luna moth tails: “They have projections off the back of the hindwing that end in twisted, cupped paddles. These studies aimed to delve deeper into the potential benefits or hidden costs of these tails. Previous studies have shown that Luna moths, along with other silkmoths, utilize their lengthy, trailing tails to evade bat attacks. In a groundbreaking investigation into the world of Luna moths, Actias luna, researchers have conducted two complementary studies to explore the role of the insects’ tails in predation and sexual selection.

Lunar moth lifespan