Cicadas: the concert begins in the abdomen

A cicada’s sound does not come from miniature vocal cords. The University of Connecticut describes two ribbed membranes called tymbals in male periodical cicadas, positioned in the first abdominal segment. Powerful muscles move them rapidly, while the body contributes resonance. The important principle is a vibrating surface. We do not need to imagine an insect speaking like a human to recognise that it has a highly specialised sound-producing system. [1]

The National Park Service distinguishes this mechanism from the rubbing action used by crickets. That corrects a familiar shortcut: explaining every insect sound through an image of two wings being scraped together. Different animals can achieve what sounds like a similar result with different structures. The park’s account also describes air chambers that help amplify the call; what we hear depends on more than the part being moved. [2]

Our editors offer a deliberately limited comparison. Touch an elastic surface and let it return, and you can imagine a repeated vibration; a surrounding cavity can change how it sounds. We have not recreated a cicada’s mechanism, and are not suggesting handling the insect. The comparison simply separates two functions: making a vibration and allowing it to resonate. The actual biological structures remain those described by the researchers, rather than the objects in our example. [1]

Females should not, however, be dismissed as an audience that is necessarily silent. In periodical cicadas of the genus Magicicada, the same source documents signals involving rapid wing movements timed to male calls. These can have both visual and acoustic components. That behaviour differs from the song produced with tymbals. This qualification matters: a simple explanation stays accurate when it names the group concerned, instead of turning a difference into an absolute rule. [1]

Hearing a chorus in the trees does not let us distinguish all these components by itself. Our suggested observation is to keep a distance, note where the sound seems to come from and describe its rhythm in your own words. This is not a sufficient method for identifying a species. The pages consulted explain mechanisms and behaviour, but sound captured on a phone, or remembered after a walk, cannot replace specialist comparison. [1][2]

Connecticut also describes chorusing groups and differences between cicada groups. Not every statement about their behaviour applies to every species everywhere. That is the most interesting discovery behind the concert: bodies generate signals, other bodies perceive them, and responses depend on context. We can appreciate that system without assigning it invented human conversations or intentions, or imagining one sound-making recipe that explains every insect we hear. [1]