Nature: Brood X cicada emergence an entomological 17-year wonder
May 16, 2021
About now, an insect army of epic scale is emerging from the earth. The periodical cicada Brood X has spent the past 17 years out of sight and mind. If you are so fortunate as to live in or visit one of their emergence areas, you won’t miss them.
After nearly two decades spent munching on tree roots, these fascinating insects will bust out and have their day in the sun. And a noisy entomological party it will be.
The first signs of the impending invasion is legions of dime-sized holes in the soil over tree roots. Then the cicada larvae craft short earthen chimneys around the exit holes, from which they soon emerge.
A cicada larva, or nymph, looks like something that just took a 17-year dirt nap. It’s the color of dried mud and looks like a giant zombified honey bee. Emergence usually happens under cover of darkness, and the nymphs promptly climb short distances up trees or other vertical objects.
Once firmly ensconced on a perch, an amazing process known as ecdysis occurs. The larval skin is shed, and out comes the beautiful adult that you see in the accompanying photo. The bug quickly hardens and is ready to fly the next day.
Then comes the fun. Males waste little time in tuning up their timbals — the drum-like sound-making organs in their abdomen. A singer produces a song that sounds like a foghorn amplified through a stack of Marshall amps: WOOEE-AWW! WOOEE-AWW! Countless thousands going simultaneously is deafening.
Three species of 17-year cicadas comprise Brood X, but Magicicada septemdecim is most numerous and its song the most prominent of the chorus.
Once the male has worked its aural magic, enticed a female and mated, she uses her sharp ovipositor to lay eggs in the wood of tree twigs. This process can kill branch tips, and dead leaf “flagging” is a giveaway that it’s a cicada egg site. No permanent damage occurs to the host tree, though. After about eight weeks, the nymphs drop to the ground, dig in and start the long cycle anew.
Brood X occurs in a patchy distribution in most states east of the Mississippi River. Billions of bugs comprise the hatch — so overwhelming in numbers are the cicadas that one must ask: Why?!
Periodical cicada reproduction is a classic predator satiation strategy. Such carpet-bombing reproduction ensures cicadas survive the predatorial gauntlet. Critters great and small snap them up until they can eat no more. Birds of all kinds, mice, raccoons, opossums, your dog — if a critter can wolf down one of these thumb-sized protein packets, it will. Even cicadas that fall in water are gobbled up by fish, frogs and turtles.
Adventurous human foodies nosh on cicadas. I’m told they are best when freshly emerged, and have a nutty flavor.
Notable among the bird-cicada relationships are cuckoos and kites. Both black-billed and yellow-billed cuckoos will converge on cicada emergences to exploit the bounty. In such years, cuckoos can produce more eggs than they can care for and will engage in nest parasitism — females dump excessive eggs in other birds’ nests.
Mississippi and swallow-tailed kites are aerobatic insect-eating raptors. They also can appear in numbers during cicada hatches.
Rather than view the Brood X cicada emergence as an annoyance, try looking at it as a rare opportunity to see one of nature’s great spectacles. After all, you’ll have to wait until 2038 to see this brood in action again.
A good spot for cicada study should be Battelle Darby Metro Park. In addition to Franklin County, cicadas should appear in Defiance, Greene, Hamilton, Logan, Montgomery and probably adjacent counties.
We’re fortunate to have the foremost cicada researcher anywhere here in Ohio. Gene Kritsky is a professor at Mount St. Joseph University in Cincinnati. To get the complete scoop on Brood X, and lots of interesting cicada information, get Gene’s book, "Periodical Cicadas: The Brood X edition."
Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature at www.jimmccormac.blogspot.com.