Moths Are Surprisingly Indiscriminate Sex Machines

Ever wonder why there are so many crossbreeds of moths out there? There are a ton of them, and a study a team at the University of California Riverside may explain why. After a lengthy research period, entomologists have determined that male moths often use their first pheromone impressions in choosing a mate, even if the mate is not of the same exact species. Results were published in the Proceedings of the National Academy of Sciences.

Moths use pheromones—which work like olfactory fingerprints—to prevent from mating with the wrong species, and males are the only ones who can read these pheromones. Moths from differing species cannot mate, but moths of different strains can, as strains are "variants" or "forms" of the same species, though not identical in biological make-up.

The researchers studied the mating patterns of the European corn borer moth by following its 'pheromone flights' in a wind tunnel. The male moths were not able to clearly measure the pheromones in the tunnel, and often chose the first pheromone plume it encountered as a mating source.

The entomologists referred to this process as a "mental short-cut" and co-author of the study, Teun Dekker, noted that "males even fly to [pheromone] blends that were initially unattractive, and so can mate with females of different strains that they would not have approached otherwise."

That explains why there are so many cross-breeds: the moths appear to be more focused on mating with anyone putting out a mating scent, rather than being more selective about identifying their own species. It doesn't clear up the age-old question of whether moths are as cool as butterflies, but it does suggest that moths are surprisingly indiscriminate sex machines.