Perfect Pitch

ALL SUMMER LONG, MALE FIELD CRICKETS CAN BE heard singing love songs to lure willing mates. But female crickets are not the only creatures these songs attract. Researchers reporting in Science magazine say they have found a tiny fly of the Ormia genus that can home in on a singing male as quickly as any lovesick cricket. How do they do it? With a hearing organ that works remarkably like a cricket's ear.

Mosquitoes and other flies that make noise have feathery antennas to pick up low-frequency fly buzzing. Crickets, by contrast, make high-frequency chirps that require mechanisms much akin to eardrums to hear these sounds.

In a classic example of what scientists call evolutionary convergence, female Ormia flies and female crickets have developed similar eardrum-like devices to serve differing goals: female crickets need male crickets to mate; female flies also need male crickets to reproduce. They use them as depositories for parasitic larvae that infest, feed on and ultimately kill their hosts.