To Compete With the Big Guys, Tiny Crickets Fashion Leafy Megaphones to Blast Their Mating Calls

Using leaves can make male crickets’ calls three times louder, upping their chances of attracting a female

A close-up photo of a bright yellow-green cricket sitting atop a large green leaf.
Though several animal species like chimps, crows and elephants have been documented using tools, it's pretty rare in the insect world. Katja Schulz via Flickr under CC BY 2.0

If you step outside on a warm summer night, you'll likely hear the shrills and trills of male crickets beating their wings together, drumming their tiny hearts out hoping to attract a female mate. The females have the upper hand in this relationship, and they choose males with the loudest, showiest calls. Calls that pass the bar usually belong to large males, leaving the little guys high and dry.

To have a shot at mating, smaller and quieter male crickets fashion their own megaphones by cutting out holes in the center of leaves, a new study finds. When they stick their heads through the leaf, their calls are two or three times as loud—and the females come flocking, reports Jonathan Lambert for Science News.

The behavior, dubbed "baffling," was first described it in the 1970s, but they didn't really know how or why male crickets did it. Lead author Rittik Deb, a biologist at the National Center for Biological Sciences in India, first observed this behavior for himself in 2008 when he saw a male cricket the size of a corn kernel cut a hole in a leaf, shove his head through and begin to drum, reports Katherine J. Wu of the New York Times.

"We humans boast about loudspeakers, but they have evolved to make such a simple structure," Deb tells the Times. "I don’t have exact words for the joy that I felt."

To finally get to the bottom of this bizarre behavior, Deb and his team "eavesdropped" on Oecanthus henryi, a species of tree crickets found in India, both in the lab and in the wild, reports the Times.

They found that baffling males tended to be smaller than those who didn't, they report in a study published this week in the journal Proceedings of the Royal Society B. Since large males don't need to be any louder, only the smaller ones baffled in an effort to woo females, writes Bob Yirka for Phys.org.

Being large might help male crickets get ahead, but "there are many ways of being attractive," Tamra Mendelson, an ecologist and evolutionary biologist at the University of Maryland, Baltimore County, who was not involved in the study, tells the Times.

Not only did small crickets have a better shot at mating when they amplified their calls, but the females also mated with them for a longer period of time. Females mate with large males for about 40 minutes, but quiet, small males only get about 10 minutes of the female's attention. In a surprising twist, small males that blasted their calls through megaphones enjoyed lengthy love-making sessions usually reserved only for big boys, reports Science News.

"They’re not wrapping their little arms around males to see whether they’re big or small," Marlene Zuk, an evolutionary biologist at the University of Minnesota who was not involved in the study, tells Science News. "Maybe there’s something in the song that signals 'go ahead and have more of this guy’s babies.'"

Though several animal species like chimps, crows and elephants have been documented using tools, it's pretty rare in the insect world. But even seemingly simple animals can exhibit sophisticated behavior, Deb tells Science News.