When they’re threatened by a predator, the larvae of Nessus sphinx hawkmoth caterpillars (Amphion floridensis) produce a high-pitched “whistle” by forcing air out of their mouths. Researchers reported the finding on Monday (February 26) in the Journal of Experimental Biology.
“This is really remarkable, considering that caterpillars are not considered to be ‘acoustic’ insects,” study coauthor Jayne Yack, a neuroethologist at Carleton University, says in a press release. “We have discovered four completely different ways that they make sounds.”
By analyzing sound waves, the researchers deduced that the caterpillar produced the vocalizations by forcing air through a tight space between its crop, a part of the throat where it packs food to eat later, and its esophagus, similar to blowing air across the mouth of a bottle. But they don’t yet know how the animal draws air into its gut, or which throat muscles it uses to produce sound. “With synchrotron X-ray visualization, we may be able to do this at higher speeds in the near future,” says Yack.
C.A. Rosi-Denadai et al., “Vocalization in caterpillars: a novel sound-producing mechanism for insects,” J Exp Biol, doi:10.1242/jeb.169466, 2018.