If a tree cricket calls out in the forest and no one hears it, really, what is the point?
Male tree crickets typically “call out” to potential mates by rubbing their wings together to make a sound. Females track down potential mates by following their sound. But it can be hard for smaller and softer-calling crickets to make themselves heard.
So, the male of the species Oecanthus henryi — a tiny, nocturnal, bush-dwelling creature found widely in southern India — uses an unusual tactic to give himself a better shot at being heard.
It fashions for itself a sound amplifier!
In an alternative reproductive tactic (or ART) called baffling, the Oecanthus henryi makes an acoustic baffle, or a sort of megaphone, by nibbling at a large leaf in its host plant until there is a hole at the centre. It then positions itself in this hole and aligns its wings with it such that, when rubbed together, their sound is amplified to almost double the original volume.
What’s interesting is that not all O. henryi crickets use a baffle. “It is usually the quieter and smaller ones that do,” says Sambita Modak, who has a PhD from the Centre for Ecological Sciences at the Indian Institute of Science, Bengaluru, and has researched baffling behaviour in this species.
Males that are naturally louder rarely use a baffle, because too loud a sound can disorient the females, making it harder for the female to find the male. And the louder males simply don’t need to take that risk.
The baffling works fairly effectively, meanwhile, for the softly-calling males, drawing more mates to them than they would get without the little amplifier fashioned out of a leaf.
“Isn’t that a fascinating instance of insect tool-making behaviour?” says Modak.
Something to think about the next time you hear the sound of wings frantically rubbing against each other.
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