You may have heard of a rare huge crop of cicadas coming out in the U.S. this year, but a local entomologist says that in Northern Virginia it’ll be business as usual.
Douglas Pfeiffer, a professor of entomology at Virginia Tech, says other areas of the country will get hit with a double whammy of periodic cicadas: a brood of 13-year cicadas that’s emerging in the deep South into part of Illinois, and another brood of 17-year cicadas known as the Northern Illinois brood. “It’s called that for a reason,” Pfeiffer cracks.
A brood of 13-year cicadas will show up in southern Virginia, moving up the coastal plain and possibly reaching Richmond, he adds. But in western and Northern Virginia, “We’re really not expecting any.”
So there won’t be a whole of lot dead cicadas to step on, as there were a few years ago. And while that might not actually be a bummer, it’s never a bad time to learn more about cicadas, and Pfeiffer pointed out some fascinating facts about periodic cicadas (as opposed to annual cicadas, which are nowhere near as intrusive or annoying).
The 13-year and 17-year cycles of periodic cicadas are significant because they’re prime numbers, Pfeiffer says that makes it very hard for predators to time their own reproductive cycles to emerge at the same time. And those cycles don’t sync up often: “It takes more than 200 years for that to happen. But that’s what’s going on now.”
Their other defense is what Pfeiffer calls “predator satiation.” The rest of us would call it sheer numbers. Pfeiffer says, “They come out in such high numbers that there’s no way that a predator could put a dent in the population.”
Pfeiffer says that while annual cicadas come out every year, they’re three to five years in the making. And because they’re there annually, they have natural predators, including wasps that — grossness alert capture cicadas, sting them, drag them back to the burrow, and use them as a nursery for their eggs. “It’s a pretty fearsome-looking wasp,” Pfeiffer says, “but they’re really not aggressive.”
Neither are the cicadas. “We don’t really ever think about trying to treat for annual cicadas,” Pfeiffer says. “It’s just periodical cicadas, because they come out in such overwhelming numbers, they would really cause noticeable injury on trees and shrubs,” especially younger ones.
As with most animals, human development and encroachment play havoc with their populations: “When you take away trees, you take away the cicadas,” Pfeiffer says. He also points out that cicadas put nutrients back in the soil when they die, serve as food for other insects and mammals, and since they don’t use toxic defenses, they’re safe for other animals to eat.
And while you might breathe a sigh of relief that there won’t be a huge influx this year, that’s not unanimous, Pfeiffer says.
“A lot of people find it really a fascinating phenomenon to live through; they’re beautiful insects. And if you don’t like it, you can just take some comfort in the fact that it won’t last long, just a few weeks, and then they’re gone for 13 or 17 years,” living underground and developing.
Feature image by Shannon Potter for Unsplash
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