The 17 Year Itch

That sound you hear isn’t the Six Million Dollar Man using his bionic powers. It’s cicadas by the billions. Every year, at least a few cicadas emerge during late spring and serenade us with their mating call. Chunky and scary looking, these insects are totally harmless but to me at least, just hearing them makes it feel a little hotter and muggier. 

This year is a little louder than most. Brood X, the largest brood of periodical cicadas, is emerging after 17 years underground in the larval stage. They’ve been tapping into tree roots during that time and now that they’ve reached adulthood they’re ready to go out in a blaze of noisy glory. They'll mate soon, lay their eggs in the tree tops, and die. When the eggs hatch, the larval cicadas will drop from the tree, burrow into the ground, and start the timer on another 17 years.

Expect it to be a little louder than usual in the Northeast
(From "This Is Spinal Tap")

All those bugs means not just a lot of noise, but also a lot of food for just about everything. The reason cicadas emerge by the billions is to overwhelm their predators’ stomachs. The strategy is that lots of cicadas will get eaten, but based on sheer numbers, many will survive to continue the life cycle for another 17 years. 

Periodical cicada (NPS)

Speaking of 17 years, why such an odd number? It’s another evolutionary strategy. What other critter can you think of with a 17 year life cycle? It reduces the risk of broods emerging during a population boom for a predator species. As a double failsafe, broods have stragglers that emerge either before or after the 17 year period.  Most are within a 13 to 21 year period. It gives the brood a better chance of survival in the event that the 17th year is a boom year for predators. 

Molting cicada (Baltimore Sun)

I've never seen a cicada coming out of its shell. Like all insects, they have a hard exoskelton, and immediately after emerging they molt. From what I'm being told, people all over are finding a lot of those shells on tree trunks and other surfaces. I haven't seen any yet this year, but I haven't been able to get outside much other than a birding expedition to New Jersey which you can read about later. This week's information comes from the University of Connecticut.