Two noisy insect broods will emerge simultaneously in Illinois for first time in 200 years
Southwestern Illinois sees cicadas every year, but this season will see an “interesting phenomenon” of the insects in the state.
Two periodic cicada broods will emerge in Illinois this spring for the first time in years. Brood 19, also known as the great southern brood, emerges once every 13 years, and Brood 13, or the great northern Illinois brood, which comes out every 17 years.
What makes this year even more special is the two broods will coincide for the first time since 1803, Jim Fredericks, board-certified entomologist and senior vice president of public affairs for the National Pest Management Association, recently told the News-Democrat.
“They’ll all emerge over the course of a couple of weeks, and there will be hundreds of thousands of cicadas that are flying around, making a lot of noise, calling for mates,” Fredericks said.
The female cicadas will each lay about 500 eggs on the tips of tree branches, and all the adults will die roughly four to six weeks after emerging. The eggs will then hatch, fall to the ground and bury into the soil. The next stage in the life cycle of the cicada, the nymph, will burrow, find tree roots and feed on them for 13 or 17 years, depending on the brood.
Brood 13 will emerge in northern Illinois, southern Wisconsin, northwestern Indiana and eastern Iowa, Fredericks said, and won’t be seen in Illinois again until 2041. Brood 19 will consist of four cicada species, which will emerge across 13 states.
These periodical cicadas emerge in the spring, as opposed to the annual ones that come out in late summer. They are typically darker in color and a bit smaller than annual cicadas, Fredericks added.
Scientists believe part of the reason periodical cicadas emerge on this type of schedule is because 13 and 17, the number of years in the cycles of these two broods, are prime numbers and are difficult for predators to follow.
“So it’s very rare that these cycles would ever sync up, so if you think about a predator that might be eating cicadas, it’s hard for their cycles to sync up with something like that,” Fredericks said.
The place most likely to see overlap between the two broods is Springfield, Fredericks said, though the Land of Lincoln will see plenty of cicadas statewide.
Illinois will likely see the two periodical broods emerge around May or early June, Fredericks continued, though they use environmental cues to decide when to come out. They are generally expected to emerge when the soil at about 8 inches deep reaches 64 degrees Fahrenheit.
Although several species will come out en masse in the same locations, the species will not interbreed. Each species has its own unique mating song the males sing, Fredericks said, and scientists have studied the soundwave patterns and can identify species just by their song.
The cicadas’ songs will be an “amazing natural spectacle” this year, Fredericks said, and the insects can be heard from up to half a mile away.
Benefits of cicadas
Unlike pests such as rodents and ticks, cicadas do not cause property damage or harm to human health.
“They’re harmless, and they really are just something to be admired,” Fredericks said.
Cicadas are an immense food source for birds and small mammals, as they are high in protein and provide the animals with a calorie boost.
Although the nymphs feed on tree roots for up to 17 years, they do not have a negative effect on the trees, Fredericks said.
Since the females lay their eggs on new branches, they may cause some dead leaves in older trees, but won’t really hurt them, he continued. Young trees can be negatively affected by too many cicadas, and you can cover them with netting to protect them.
In addition to providing an important food source, cicadas also benefit the environment by aerating lawns, improving water filtration and adding nutrients into the soil, according to the U.S. Environmental Protection Agency.
