MINNEAPOLIS — Insect enthusiasts are gearing up this year for an event that hasn’t happened in 221 years, the dual emergence of two periodical cicadas.
Billions of singing bugs will appear in parts of the Eastern United States when Brood XIII and Brood XIX both arrive in the same year.
The cicadas in Brood XIX, or Brood 19, emerge from the ground once every 13 years, while those from Brood XIII, or Brood 13, emerge once every 17 years. In some places, both the 13-year cicadas and the 17-year ones will come crawling out of the earth at the same time.
“The last time these two specific broods emerged together was 1803 when Thomas Jefferson was president of the United States,” Gene Kritsky, Professor Emeritus of Biology at Mount Saint Joseph University in Cincinnati, told KARE 11.
“When it happens in your neck of the woods it’s like having a David Attenborough special in your backyard. It’s just an amazing scene from nature!”
Professor Kritsky has been studying and mapping periodical cicadas for decades and has just published a book about the dual emergence event. His wife, Jessee Smith, is a metalsmith and artist who produces insect-themed jewelry, including cicada pieces.
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Minnesota is too far north to get periodical cicadas, but Kritsky says those who travel to southern Wisconsin or the Chicago suburbs should be in for a pretty good bug show this spring. Sangamon County in central Illinois is one of the spots expected to see both the 17-year cicadas and the 13-year variety.
"They start emerging when the ground reaches 64 degrees Fahrenheit. So, it will start in the Southern states, probably the last week of April and then slowly move up north arriving in southern Wisconsin probably the first of June."
University of Minnesota entomologist Vera Krischik is also excited about the big cicada event and plans to travel to states where it’s happening.
"I wouldn't miss it for the world. This is fun for us entomologists!" Krischik told KARE 11.
She said researchers will be taking a deep dive into the physiology of the bugs, their diseases, movements and mating songs. But many experts will take joy in just watching regular people react to the swarms.
"Every entomologist has a kid inside and all those kids just want to watch the civilians, the non-entomologists, squeal as these cicadas are all over the place. That's our fun!" Krischik remarked.
"They can’t hurt you. Even if you pick them up. They have spines on their legs, so you think they’re biting you but they’re not."
Periodical cicadas have black bodies, red eyes, and wings with orange veins. Minnesota’s annual cicadas, by contrast, are greenish with green veins on their wings. Those are known as Dog Day Cicadas, named for the dog days of summer.
In Minnesota you’re more likely to see the exoskeleton, or the empty shell of a cicada nymph, clinging to the tree after it has molted into the adult stage and opened its wings. You can hear them singing but they tend to blend into the foliage.
"They mate, the female lays eggs on the tips of maples and other deciduous trees on the edge of the forest," Krischik explained.
"The eggs hatch into little nymphs, the nymphs burrow out of the twigs, they fall to the ground, attach themselves to the roots, and they feed for another year and come out the next year."
There is no clear explanation as to why some cicadas come every year, while others spend 13 or 17 years in the ground as nymphs waiting to emerge. Avoiding predators is one likely explanation.
"Predators like birds and mammals can’t keep track of 13 years or 17 years and they’re not going to be there waiting to eat them," she explained. "With an annual cicada, birds or mice or raccoons, they can remember and go back to the same tree the next year at the same time and eat the cicada."
In Minnesota, the annual cicadas can also fall victim to cicada-killer wasps. They sting the cicadas and lay an egg in them simultaneously, allowing the wasp larvae to feed off a living host.
Kritsky said the periodical cicadas survive in part because so many arrive at the same time.
"They come out in massive numbers to essentially overwhelm their predators, so their predators can eat all the cicadas they want and get sick of eating them, and there's still millions of them left."
Mount Saint Joseph created the Cicada Safari smartphone app, a crowd-sourcing tool that allows people to report cicada sightings and post pics tied to their GPS coordinates.
"Each photograph is accepted by our servers and then is looked at by people who are trained to identify periodical cicadas, and if it’s approved it goes onto a map live," Kritsky explained.
It got its first test run in 2021 when Brood X, a 17-year cicada, emerged.
"In 2021, which was the big event we wanted to get this ready for, we had 200,000 downloads and received half a million photographs!"
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