Noise Makes Grasshoppers Change Their Tune For Mating

By Nick Venable | 8 years ago

Where I live, the cricket population is larger than the grasshopper population, but I still hear them. My parents’ home isn’t in the country, but it’s got a swath of trees on two sides, and traffic noise is rarely an issue, so bug noise is prevalent. I live in a populated subdivision now, with a lot of fields surrounding the outskirts of the properties, and traffic noise is louder. But the bugs are still prevalent. And never in all of these years has it occurred to me that where I lived would affect the location of those bug noises. Not because of my being there, of course, but because of the proximity to traffic noise.

The noises of the grasshopper, and animals in general, aren’t incidental. They aren’t just making music because they’re Libras and they have music in their soul. It’s about mating, and safety, and more mating. Grasshoppers rub the toothy file on their back legs against a vein on their front wings to make their signature noise. For mating.

Ulrike Lampe and colleagues from the University of Bielefeld in Germany used 188 male bow-winged grasshoppers as their test subjects. Half of the insects were from beside busy roads, and the other half came from less noisy areas. They were exposed to female grasshoppers, and their accompanying songs, probably wimpy ballads, were recorded. Almost 1,000 recordings of what was essentially grasshopper foreplay were analyzed, and their songs were found to be quite different. The low end of their frequencies had to be upped to match the low din of car engines and E-40’s bass.

Much like a drunken man’s karaoke renderings of non-grasshopper ballads, the effect of these mating songs is affected by traffic, and could affect the “females’ ability to estimate how attractive a male is from his song,” says Lampe. If only modern rock songs conveyed the rapist look the lead singer conveyed. The songs are two second-long “phrases” that increase in amplitude. Tick-tick-rrrt. Or something. It’s all about the vibrations in the grasshopper legs that make this noise. Vibrations. For mating.

But seriously, it’s not like grasshoppers have just recently started living in grass next to interstates and highways. The goal is now to understand the mechanism involved, and figure out at what stage of life the grasshopper adapts to this behavior, and if it’s genetic or affected. I’m no scientist, but I’m thinking it’s genetic, because these guys are born to mate.

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