Brief moment of thinking "it's a good thing cicadas stick to the tallest trees in an area so they're really high up with leaves in the way, it helps dampen their noise to keep it tolerable instead of making every brood year a FREE! introduction to hearing damage for the rest of us"

And then I remembered they do that because they have to. they have to pick the oldest trees. they spend so long underground nibbling on roots that they literally cannot get by with young trees. they naturally and unavoidably cluster up around the sturdiest trees which were already old enough to have a root system to support them, which in practice means the oldest and generally tallest trees. This is a "water flows downhill because gravity exists" sort of arrangement.

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(Yes adults can and do fly around a bit, but the adults also have opinions about what branches are good for eggs, and once again those branches are generally found on the largest and sturdiest trees. Cicadas don't seem to prioritize tree age/height per se but if you line up enough correlating factors it's what you get!)

(This is also why the majesty of brood years in a given locale is basically linear with how good the tree situation is: you can't just have trees, you need to have a functionally unbroken chain of really good big/old trees going back forever, close enough together for half-blind adults to find, so that the larva have their 13/17 years of life support and adults have somewhere to drop the eggs off. Just replanting won't fix it if all the trees in an area get chopped down, which is why some broods have gone extinct within the last 200 years. )