A caterpillar-like beetle hangs on a stem and goes about its business. Suddenly, tongs appear, approaching the creature. As soon as they touch the stocky insect, it hisses and jerks its body from side to side.
The irritated individual is a mature larva of the yellow-leaved hawkmoth (Unlike Phillosphingia), and his irritation is justified, since the tongs are designed to imitate a predator. In fact, this is desirable. This scene is from a laboratory where researchers were studying how the larvae and pupae of this species make shockingly noisy defensive sounds.
Hawkmoth larvae and pupae make sounds through spiracles / Hawkmoth larvae and pupae make sounds through spiracles
Scientists have previously documented that some moths produce sounds to ward off predators at various life stages. “We became interested in this topic when we noticed that hawkmoth larvae and pupae made surprisingly loud sounds when stimulated,” Shinji SugiuraKobe University ecologist and co-author study recently published in Journal of Experimental Biology, says the statement. Larva This is the second stage of metamorphosis in many insects, occurring after the animal hatches from the egg and before it becomes a pupa.
To study this noise, Sugiura and his colleagues conducted experiments on yellow-leaved hawkmoth larvae and pupae in which they simulated an attack similar to a bird's peck or a predator's bite by touching the insects with forceps. During the simulation, they noted the resulting noise and body movements of the animals, and also analyzed the participation of their internal organs in the production of sound.
According to the study, most of their mature larvae and half of their pupae responded to physical contact with noise and rapid movements. The team conducted some of their tests underwater and found that the animals' breathing holes emitted a hissing sound, forming bubbles.
“Until now, it was believed that sound production in pupae occurs only through physical friction between body parts or against a substrate. This is the first evidence demonstrating a sound production mechanism in pupae that is driven by forced air supply,” Sugiura explained.
“The larvae and pupae of this species have one pair of small holes (spiracles) on the thorax and eight pairs on the abdomen. Through these spiracles they absorb air,” he added. Popular Science. “In this species, larvae and pupae make sounds by expelling air through special spiracles, like a whistle.”
Except that the noise itself doesn't sound like a whistle. The sounds of buff hawkmoth larvae and pupae are comparable to the warning sounds of snakes.
“Because hawkmoth larvae and pupae are likely to be preyed upon by birds and small mammals—animals that may themselves be attacked by snakes—we hypothesize that this species of hawkmoth acoustically mimics snakes' warning calls to protect itself,” Sugiura said in a statement.
Further research will be needed to determine whether other groups of animals have similar mechanisms and how potential predators respond to violent sounds.
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