Cicadas are coming — and if you’re in the Midwest or Southeast, they’ll be more plentiful than ever. Or at least from the Louisiana market.
This spring, for the first time since 1803, two groups of cicadas known as Brood XIX, or Great Southern Brood, and Brood XIII, or North Illinois Brood, are set to appear at the same time, in what is known as a dual. appearance.
The last time the 17-year cycle of the Northern Illinois Brood aligned with the 13-year cycle of the Great Southern Brood, Thomas Jefferson was president. After this spring, it will be another 221 years before the offspring, who are geographically adjacent, appear together again.
“Nobody alive today will see that happen again,” said Floyd W. Shockley, chairman of the Entomology Collections Committee at the Smithsonian’s National Museum of Natural History. “That’s really rather humbling.”
These insects will begin to appear in late April. They will use their front legs to emerge from the earth, their red eyes looking for a spot where they can peacefully finish maturing. A few days after they emerge and hatch, the males will begin buzzing in an attempt to find a mate, a slowly building crescendo. noise that in a chorus can be louder than one level.
Dr. Shockley said the double emergence would likely result in more than a trillion cicadas appearing in the roughly 16-state area where the two broods are generally seen. Forest lands, including urban green spaces, will have a larger number than agricultural areas. To put this in perspective, a trillion cicadas, each just over an inch long, would cover 15,782,828 miles if placed end to end.
“This train of cicadas would go to the moon and back 33 times,” he said.
One of the most exciting aspects of this double emergence, Dr. Shockley said, lies in the possibility of interbreeding along the narrow belt in northern Illinois where the two broods would overlap.
“Under the right conditions and with just the right number of individuals interbreeding,” he said, “you have the potential to create a new offspring that comes into a new cycle. This is an extremely rare event.”
In most cases, Dr. Shockley said, the cicadas, which live about a month, will die not far from where they emerged. But because they’re “not great fliers and even worse landers,” cicadas often end up on sidewalks and city streets, where they can be squished by people or cars and “could potentially make things slick.”
“In urban areas, there will be sufficient numbers to require the removal of their bodies,” he said. “But instead of throwing them in the trash or cleaning them up with street sweepers, people should think of them as basically free fertilizer for plants in their gardens and natural areas.”
According at the University of Illinois Urbana-Champaign, during a cicada outbreak in 1990, “there were reports from people in Chicago having to use snow shovels to clear their sidewalks of dead cicadas.”
The first wave of periodical cicadas, different from those that appear annually in smaller numbers, will appear in northern Louisiana, southern Arkansas, Alabama, Mississippi, northern Georgia and as far west as South Carolina, said Gene Kritsky, a retired professor biology at Mount St. Joseph in Cincinnati, and author of several books on cicadas, including “A Tale of Two Broods,” out this month.
Next will be central North Carolina, eastern Tennessee and northern Arkansas, followed by southern Missouri, southern Illinois and western Kentucky. Finally, he said, cicadas will appear throughout central and northern Missouri and Illinois, northwestern Indiana, southern Wisconsin and eastern Iowa.
In total, these areas will be buzzing for about six weeks as the insects fly around looking to mate and lay their eggs in crevices they cut in tree branches. They will then die, bringing with them an unforgettable smell, described by Dr. Shockley as similar to rotten walnuts, as their bodies decay.
Insects are clumsy flyers, making them easy prey for predators such as birds. They do not bite, sting or carry disease and serve as natural tree gardeners.
The holes they leave behind help aerate the soil and allow rainwater to seep underground and nourish tree roots in the hot summer months. The gashes they make in trees can cause some branches to break, and the leaves then turn brown in a process known as ‘flagging’. But it is like a natural pruning, and when the tree grows the branch again, the fruit will be greater. Rotting cicada bodies provide nutrients that trees need.
“They are very important to the ecosystem in the eastern deciduous forest,” said Professor Kritsky, referring to the forest ecosystem in the eastern half of the country.
John R. Cooley, a professor of biology at the University of Connecticut, said his best advice for people living in the areas of the double appearance is to let the bugs be.
“The forest is where they live.” he said. “It’s part of the forest. Don’t try to kill them. Don’t try to spray insecticide, all of it. That’s going to end badly because there’s more than you can kill with insecticide, you’re going to end up killing everything.”
If you have sensitive plants you want to protect, Professor Cooley said, use special netting made for that purpose.
While the prospect of trillions of cicadas expected to come with the double emergence may sound terrifying to some, Dr Shockley emphasized the awe of this rare natural event.
“Don’t fear it, embrace it for the wonderful event that it is and accept the fact that it’s very temporary,” he said. “It will be intense, but short-lived.”