Cricket Evolution In Hawaii Is Rare And Disturbingly Silent

Chirping is a defining trait for crickets. However, some species of cricket have evolved ‘flat wings’ to silence their chirp. This evolution is made more unusual by happing in two different habitats near the same time.

That’s called “convergent evolution”. It’s something that doesn’t happen often. The crickets began appearing around Kauai and Oahu with altered wings about ten years ago, two years apart. It was thought at first that the evolutionary traits must have traveled. Considering the amount of travel (tourist and local) between the islands it would seem easy enough to accidentally transport eggs or have hitchhiker insects.

But when examined closer, the newly evolved wings had different shapes. Experts thoroughly tested the mutant crickets and confirmed that the trait evolved separately in the X chromosome. Dr Nathan Bailey, University of St Andrews, participated in the study and said that the evolution happened, “in what appears to be the blink of an eye in evolutionary time… This is an exciting opportunity to detect genomic evolution in real time in a wild system, which has usually been quite a challenge, owing to the long timescales over which evolution acts.”

Imagining crickets without their chirp is odd and a bit sad. This kind of evolution happens when an external pressure is put onto a species. An ‘adapt to survive’ stress that requires fast action. In this case it was the introduction of killer flies.

These flies come from North America and spray baby maggots on the backs of crickets. The maggots bury in, feed, and exit a week later. The cricket, um, clearly, dies. It’s disgusting, I know. And how do these killer flies find their prey host? Chirping. The need to evolve becomes apparent. Crickets themselves are fairly recent arrivals from Australia. Migrating to the islands must’ve seemed pleasant enough. Who could’ve imagined it would turn out to be a fiercer environment than the outback?

Chirping is a necessary part of mating for crickets. The males serenade as a mating call. Since silent crickets are… silent… their new approach to mating is waiting in the same area as chirping males – then intercepting the females. It’s unclear how crickets will adapt if the silent mutation becomes dominate.

Crickets are a healthy part of the insect community, and can be a surprisingly healthy addition to the human diet. These bugs provide high amounts of protein-per-serving and can be grown in very efficient livestock-to-area ratio. Save the crickets!