Wild Thing: Shrill Symphony
Giant cicadas provide a loud, rhythmic soundtrack to Texas summers.
By Ben Hutchins
Ah, the sounds of summer: children playing, an ice cream truck in the distance and … a tree full of screaming steam engines? As the name implies, the giant cicada, Quesada gigas, is large compared to Texas’ 50-plus other cicada species (the smallest of which, Beameria venosa, could sit comfortably on a penny), but the name could be a reference to the species’ otherworldly and sometimes deafening call.
In Brazil, researchers recorded the song of the giant cicada hitting 93 decibels at a distance of 50 cm (just over 1.5 feet). That’s a bit louder than a lawnmower but not quite as loud as a jackhammer. (Permanent hearing loss can occur with prolonged exposure to volumes as low as 85 decibels.)
Although periodically recorded in the Big Bend region, eastern Hill Country and southern East Texas, giant cicadas are particularly abundant in the Lower Rio Grande Valley, where their calls have been compared to various power tools, motors, fan belts and steam engines. Indeed, the species is sometimes called the “locomotive cicada” in parts of Latin America.
Like other cicadas, that prodigious sound is generated from a pair of organs on the abdomen called tymbals. The tymbals act like tiny sheets of metal that, when flexed, produce a pair of resonant pops as they buckle inward and outward. The tymbals are flexed hundreds of times per second. Then, like the hollow body of a guitar, the sound produced by the tymbals resonates within air sacs in the cicada’s large abdomen before radiating out through a thin-membraned organ called a tympanum.
Like other cicadas, giant cicada larvae spend years underground feeding on tree roots. Larvae may be parasitized by an unusual beetle, aptly named the cicada parasite beetle.
Despite their large size and disconcerting appearance, adult cicadas neither sting nor bite. Cicadas may be consumed by a variety of animals and are notably (and horrifically) hunted and paralyzed by adult cicada killer wasps and then eaten alive by the wasp larvae.
As deafening as the giant cicada’s call is, it is not the loudest cicada in the Western Hemisphere, or even the loudest in Texas. That distinction goes to the Limpia Canyon scrub cicada, Diceroprocta cinctifera limpia, which was recorded at just over 108 decibels, beating out the jackhammer and closing in on loud chainsaws or snowmobiles.
However, the Limpia Canyon scrub cicada occurs only in the Davis Mountains of West Texas, and because it calls at a substantially higher frequency than the giant cicada, the sound fades more quickly with distance, making the giant cicada the undisputed noisiest neighbor of the Texas insect world.
Listen for the giant cicada in South Texas during the summer months, starting in June, particularly during dusk or dawn. Depending on weather conditions, the giant cicada’s call may travel a mile or more.
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