That trick allows them to be active when it's too hot for the predators that feed on them. When people talk about how it seems like it just feels hotter when they hear the cicadas, that's because they're out when it is hot. As it exits their body through pores on their thorax, they get that continuous evaporative cooling. They feed on plant sap, so they are constantly sucking in liquids, and as the temperature gets hotter and hotter, and they start to overheat, they remove the water from their blood and pass it through ducts in their body. "Cicadas have figured out a way of sweating, if you will. Why are cicadas active during the hottest part of the day? Cicadas can turn themselves into an evaporative cooler. In addition, the angle by which the insect props itself up on the twig or trunk it is sitting on helps control the resonation, like a speaker bouncing sound off a wall."ģ. That, along with hollow cavities, is how they achieve the volume. It's unique to cicadas and consists of a pair of thin, hardened membranes that they flex with specialized muscles, and that creates a clicking sound. "On the underside of their bodies, the males have a structure called a tymbal. Remember those clicker toys made from thin metal, often shaped and painted like a frog? Where you use your thumb to push and release a flexible tongue on the underside to make noise? Male cicadas produce sound in a very similar way, Hall explains. Cicadas are the loudest insects in the Southwest, and they make noise the same way as a popular vintage toy. To pick up the sound, both sexes have structures located in the front of the abdominal area, under the wings, called tympana, which basically function like an eardrum."Ģ. They also use noise to drown each other out or cancel calls from other competing for females. Some males will stay in the same spot and call continuously, whereas others will fly off and call from another spot.
Each species of cicada has its own mating call, which can range from soft clicking to loud buzzing. "Some species produce that loud whirl that we hear around here, while others make more of a soft clicking sound. "The loud noise we hear is the male's mating call - females are silent," Hall says. The body of a cicada is similar to that of a violin or a guitar, in that much of it consists of empty, air-filled spaces that act like a resonating chamber and amplify the sound they generate.
Cicadas are essentially tiny violins with wings. We talked with UA entomologist Gene Hall about cicadas and how they do the things they do. Once they're here, you know summer's here, too: You don't have to live in the desert Southwest for very long to learn that once the first cicadas of the year can be heard broadcasting their piercing buzz from invisible locations in the trees, it's time to kiss spring goodbye and say hello to the blast furnace that is June in much of Arizona. Gene Hall's position is jointly funded by the University of Arizona's College of Agriculture and Life Sciences, where he manages the insect collection, and CALS Cooperative Extension, which has him provide outreach services to the community and share his expertise in various areas, including forensics.
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