DETROIT – It’s an underground movement now, but it will be all the buzz this spring and summer.
This year will mark the reemergence after 17 years of Brood X, or the Great Eastern Brood, of periodical cicadas – those large, winged, kind of scary-looking but mostly harmless flying insects known for their almost deafening buzz.
“The end of May through June, it can get pretty loud – if you are in an area where they are numerous, there can be hundreds of thousands, or millions, of them,” said Howard Russell, an entomologist (insect scientist) at Michigan State University.
One of the largest broods of periodical cicadas in the nation, Brood X will emerge this spring in 15 states: Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, as well as Washington, D.C.
Unlike greenish, annual cicadas, periodical cicadas are known for their black bodies and bold red eyes. Their mass, in-unison emergence every 17 years is one of nature’s great mysteries.
But the bugs haven’t been in hibernation since their last mass appearance in 2004.
“They are always there – that’s what people don’t realize,” said John Cooley, an entomologist at the University of Connecticut who studies periodical cicadas.
The cicadas live underground in wingless nymph form, about a foot or two down, feeding on sap from tree roots – “and that’s where they feed for 17 years,” Russell said.
How do they all know when to resurface?
Most cicadas don’t have fixed periods of development like this. When they reach adulthood, away they go, as individuals or small groups.
But with periodical cicadas, after 17 years underground, on just the right spring day, when soil temperatures reach 64 degrees Fahrenheit, the nymphs, all together, burrow their way to the surface and make their mass emergence, Russell said.
“They climb up on the nearest thing they can find, and molt for the final time,” he said. “At that time they are white – their exoskeleton hasn’t hardened yet. That takes five or six days. Then the adult is ready to look for a mate.”
Why they aren't triggered to do this in, say, the 15th or 16th spring isn't fully understood.
“No one knows what mechanism they use to trigger their mass emergence,” Russell said.
From underground, periodical cicadas have some method of counting the number of times deciduous trees – the kind that lose their leaves in the winter – regrow their leaves, Cooley said.
“The cicadas come out after the ‘right’ number,” he said. “Whatever the specific change is, the cicadas can detect that.”
The bugs will even, in unison, postpone their emergence for a day or two if the weather is rainy or otherwise uncooperative, he said.
That telltale Brood X buzzing noise are the males up in trees, trying to attract a female.
“If you go along the Wabash River Valley, on the Illinois-Indiana border, they have all three species there at the same time,” he said. “The noise is just head-splitting.”
After mating, female periodical cicadas will lay eggs in soft, new twigs, using a sharp organ called an ovipositor to cut into the branches and place her fertilized eggs inside. That can kill young branches, which makes the periodical cicada swarm more harmful for tree nurseries and orchards.
“You can’t spray enough pesticide to kill them all without also wiping out everything else in the environment,” Cooley said.
The solution is to put nets or bags over trees for the period of time the cicadas are active, until around the start of July, he said.
Laid eggs hatch in six to 10 weeks. The tiny nymphs fall to the ground, burrowing in, and start the 17-year cycle again.
Aside from being loud – their sound is a cross between a buzz and a rattle – the cicadas really won't do any major damage. They aren't drawn indoors. They don't bite.
"While they may cause cosmetic damage to trees when laying their eggs, cicadas actually provide a number of benefits to nature," Jim Fredericks, chief entomologist for the National Pest Management Association, said in a statement.
And you can eat them
If you're so inclined, cicadas can even make a low-fat, high-protein snack. Dried cicadas provide a crunch with a nutty, earthy taste, according to those who've tried it. In their softer form, before their exoskeletons harden, others say the cicadas are shrimp-like. A group at the University of Maryland even published a periodical cicada cookbook titled Cicada-licious, featuring recipes for dishes such as Cicada Dumplings, Emergence Cookies and El Chirper tacos.
Periodical cicadas have seen some retraction of their habitat.
“They seem to be sensitive to habitat degradation,” Cooley said. “I think they are going to be very susceptible to climate change.”
The question Cooley gets the most whenever the periodical cicadas’ reemerge is how to kill them, he said.
“The answer is: don’t. They are one of our natural wonders. Enjoy them while you have them.”
This article originally appeared on Detroit Free Press: Cicadas to reemerge in US for first time in 17 years