Two sets of male crickets on neighboring Hawaiian islands have been able to avoid attracting deadly parasitic flies by simply shutting up. The crickets likely arrived from Oceania in the late 1990s, and the flies came from North America around the same time.
When the crickets tried to lure nearby females with their evening serenades—the chirping sound produced by scraping one wing across the other—they unwittingly attracted the new predators, pregnant flies who would spray maggots onto their backs.
The fly larvae would then burrow into the crickets, grow, and emerge victorious a week later, with nothing but cricket carcasses in their wake. But, scientists were surprised to discover, the cricket wings changed shape to stop producing sound over the course of just 20 generations.
In other words, “in what appears to be the blink of an eye in evolutionary time,” the lead researcher tells the BBC. Even more remarkably, scientists also found that the adaptation happened differently and independently, but almost simultaneously, in the populations on Kauai and Oahu, reports Nature—the phenomenon is known as “convergent evolution.” And though many of the crickets are now chirpless, they are doing something right; the so-called “flatwing” populations on both Kauai and Oahu are still alive and procreating, while the flies will have to devise a new way to find them. As for how the chirpless crickets find mates? They hang around the few crickets that still chirp, and then steal away some of the females that come calling.