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Cicadas - Blog Posts
the paralyzed cicadas I picked up from a failed cicada killer nest are the perfect material to show off some cool features of insect anatomy! (although the wasp’s venom would keep them alive for her larvae to eat, I froze them to make sure they’re fully dead for dissection).
cicadas are powerful, fast fliers, and all of their thorax is taken up by a bulk of reddish, stringy flight muscles, which I’ll talk more about later. this cicada is a female, so her abdomen is full of white, elongated eggs that she will insert into tree bark with the bladed ovipositor at her rear.
the male cicada’s abdomen, however, is almost entirely empty, and that air-filled space is used as a resonator for his loud calls. the biggest structure visible there is a curved pair of muscles that deforms the tymbals, producing a click with every contraction.
here's a view of the complete muscle, and the tymbals themselves which look like overlapping plates on his belly. if you're curious what the white frosted appearance is, some Neotibicen have a coat of waxy powder or pruinescence; this male N. tibicen is particularly pruinose.
onto the flight muscles:
powered flight is a pretty complex mechanism in any organism, and is never so simple as just flapping wings up and down, but most insects power their flight in a really unintuitive way (at least for us vertebrates): they contract muscles in their thorax that aren’t even attached to the wings!
this method of flight is called indirect flight, in contrast to the direct flight of the dragonflies and mayflies where each of four wings is directly attached to a muscle and can flap on its own.
instead, most insects have a longitudinal (image 1 above, d below) pair and a vertical (2, c) pair of muscles that deform the shape of abdomen, pulling the upper segment of the thorax (notum) up and down, and this moves the wings which are attached to the notum. useful indirect flight gif from wikipedia found here
even if compressed manually, the dead cicadas "flap" their wings due to the motion of the notum:
insect flight is a lot more complicated than this simplified look at them, but I think these cicadas offer a pretty good look at how most insects get around essentially by squishing themselves internally!