When we think of cicadas, we think of the spring time periodic cicadas that emerge en masse, in some years, by the billions and billions. There are also annual cicadas and they typically emerge in late summer or the “dog days” of summer, hence the name, Dog Day Cicada.
Our daughter Liv spotted a Dog Day Cicada atop a 5-foot tall stalk of the Marsh Mallow plant.
Dog Day Cicadas are about half an inch larger than the periodic cicadas. We hear male Dog Day Cicadas in our gardens and neighborhoods and they are one of the wonderfully familiar sounds that immediately brings to mind the music of sultry summer nights. Unlike periodic Cicadas. Dog Day Cicadas emerge singularly; they need to “scream” loudly to attract a female.
Song of the Dog Day Cicada. You can hear the Cicada at about 4 seconds in.
The astonishingly loud sound that is emitted by cicadas comes from a pair of organs called “tympana” located at the base of the males’s abdomen.
Musical Geniuses
Arizona State University, “Ask a Biologist.”
Cicadas are most well-known for their very loud, constant chorus of song during the summer season. Although they sort of sound like crickets, it is pretty clear that cicadas are bigger and better at bringing the noise.
While crickets rub their wings together, male cicadas use a different, louder part of their bodies to make noise. Both sides of their thoraxes have thin, ridged areas of their exoskeletons called tymbals. Tymbals are made of a rubbery substance called resilin. The cicadas vibrate their tymbals very fast using muscles in their bodies. With every vibration, a sound wave is released, and cicadas can send out 300-400 sound waves per second! Females also make sounds to attract males, but they use their wings to make a clicking sound, rather than a high-pitched song like the males.
The cicadas you hear singing long into the night are male cicadas looking for females to mate with. Males are so loud because they have a couple other sound features that allow them to make very loud continuous noises. The abdomen of male cicadas are almost completely hollow. When sound waves from the tymbals enter this hollow area, they bounce around. This can change the sound, make the sound louder, or both.
Different size and shape cicada abdomens will change the sound in different ways. This explains why different cicada species make different noises. Cicadas, and all insects for that matter, also have hollow tubes running through their body called trachea. Trachea move oxygen and carbon dioxide around, sort of like our lungs. Trachea are also hollow, so they are also used by the cicada to make their songs louder. All in all, the cicada is one complicated insect instrument!
