Cicadas Illinois

Illinois' historic cicada emergence is winding down, but another cicada is coming

The season started with the emergence of not one but two major periodical cicada broods, which haven't emerged simultaneously in more than 220 years, but there's also a third on the way

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While the great cicada emergence of 2024 may be coming to an end, the "summer of cicadas" is far from over, and the next round might look a little different.

That's because another emergence is on the horizon.

The season started with the emergence of not one but two major periodical cicada broods, which haven't emerged simultaneously in more than 220 years.

But while the two periodical cicada broods emerge every 13 or 17 years, there's also an annual cicada that emerges every summer: Illinois' annual "dog day" cicadas.

"Not only do we get the cicadas every 17 years," said Allen Lawrance, associate curator of entomology at the Peggy Notebaert Nature Museum in Chicago. "We do get some every single year. Those are our annual cicadas. Those are larger and green."

There are other differences between Illinois' periodical cicadas and annual cicadas, Lawrance said.

"Periodical cicadas are smaller than our annual cicadas," Lawrance said. "You can see their bodies are a little bit thinner, a little bit more cylindrical shaped."

Lawrance noted that annual cicadas, which emerge in Illinois every summer, are more "robust," and typically louder than periodical ones. But there's power in numbers, Lawrance said.

"[Periodical cicadas] are not as loud individually, but because there's so many more of them, their song overall is louder," Lawrance said, with billions periodicals from Broods XIII and XIX expected in Illinois.

When will 'dog day' cicadas come out in Illinois?

Illinois' annual cicadas can be expected to emerge in July, August and September, an article from the University of Illinois Extension said.

"It typically takes 2 to 5 years to complete their development and they have overlapping generations and are not synchronized," the article said. "On the other hand, periodical cicadas take 13 or 17 years to complete their development from egg to adult, and they emerge in mass in the spring."

While periodical cicadas begin to emerge once the soil temperature reaches 64 degrees, "dog day" cicadas emerge from the soil "during the heat of the summer, or the dog days of summer," the article explained.

The periodical cicadas will be gone by the time the annual ones emerge, Lawrance said. Still, in Illinois, this spring and summer may feel like the season of the cicada.

"There's really no escaping them," Lawrance said, especially on and around trees, where "piles" of cicada shells are expected after the insects have feasted on fluid from branches and woody shrubs.

"You're just going to see them sort of flying around, hanging out on trees," Lawrance said. "And you're going to hear them wherever you go."

What else is coming?

Beyond the dog day cicadas, there's also still the matter of the periodical cicadas' eggs.

The hatching takes place between six and 10 weeks after eggs are laid and while it is rare to catch a glimpse of the moment, Kritsky said when conditions are right, the moment could be viewable in the Chicago area.

"If the sun is at the right angle, people have actually seen the nymphs falling to the ground," Kritsky said, noting the sun would need to be behind the tree where the eggs are hatching, "illuminating them as they drop."

Trees in areas that saw large emergences could have as many as 40,000 eggs waiting to hatch, he added.

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