Hawaii’s male crickets thought they had outwitted their winged stalkers. They evolved a subtle, purring mating call—less rock concert, more whispered romance. The goal? Attract females without inviting a gruesome death.
But evolution is rarely a one-sided affair. The parasitic fly *Ormia ochracea* wasn’t about to let dinner slip away. In less than a decade, the flies have fine-tuned their hearing, decoding the crickets’ new, covert signals like biological surveillance drones.
The setup for this microscopic war began in 1989, when *O. ochracea* landed in Hawaii. Native to continental North America, the flies came bearing a particularly nasty trick: They locate crickets by eavesdropping on their chirps, then deposit larvae onto their unsuspecting hosts. The maggots burrow in, feast on their living meal, and emerge victorious. For crickets, successful romance often ends in horrific body horror.
Crickets did the only sensible thing—adapt or die. A mutation reshaped the wings of some males, transforming their usual chirping into a bizarre, rattling purr. This softer, less conspicuous love song kept them off the flies’ radar while still wooing female crickets. It seemed like a decent workaround.
But scientists, ever suspicious of nature’s patience, wanted to know: Would the flies strike back?
Robin Tinghitella, an evolutionary biologist at the University of Denver, decided to investigate. Her team brought both Hawaiian and Floridian *O. ochracea* flies into the lab and tested their auditory neurons. Could the Hawaiian flies pick up on the new, quieter cricket songs?
Oh, absolutely. Not only were the Hawaiian flies more sensitive to the cricket purrs, but they physically moved toward the sound. Fewer decibels wouldn’t save the crickets—not when the enemy was evolving in real time.
To confirm these findings in the wild, researchers rigged up some fly traps in Hawaii. The bait? Cricket songs, both the traditional chirps and the newly evolved purrs. Nearly 20% of the trapped flies were lured in by the crickets’ hushed whispers—proof that the flies were already catching on.
Tinghitella calls this a case of “adaptation and coadaptation,” a classic evolutionary arms race. Crickets tweak their signals, flies adjust their sensors, and the cycle repeats, an endless biological chess match with survival at stake.
Neuroethologist Norman Lee from St. Olaf College suggests that mapping out the flies’ evolving hearing abilities might help predict the crickets’ next moves. Maybe they’ll go even quieter. Maybe they’ll ditch sound altogether and switch to vibrations. Maybe they’ll develop an underground speakeasy for romance.
For now, the battle continues. The crickets whisper, the flies listen, and evolution refuses to rest.
Five Fast Facts
- *Ormia ochracea*’s hearing is so sensitive, it has inspired the development of ultra-precise directional microphones for hearing aids.
- Crickets have existed for over 200 million years—meaning some of their ancestors may have chirped at dinosaurs.
- Hawaii has no native terrestrial amphibians or reptiles, which means crickets and their predators have evolved in a uniquely isolated environment.
- Male crickets don’t just sing to attract mates—they also use chirps to intimidate rival males before fights.
- Some species of crickets can regenerate lost limbs, but unfortunately for the *Teleogryllus oceanicus*, this won’t save them from fly larvae.