Cicada Synchronicity

A typical swarm of periodic cicadas. Photo by Allen Lawrance

words by Kris Hansen
photos by Allen Lawrance

They’re so close. The nymphs of the 13-year and 17-year cicadas are just under the surface of the soil, checking out conditions above while they wait for the perfect warm day in May to emerge. And when they do, they will arrive in the trillions.

When researchers estimated counts of the 17-year cicadas that emerged in 1956, “near the Chicago area, there were densities of above a million, or even up to 1.5 million, [cicadas] per acre emerging,” says Allen Lawrance, associate curator of entomology for the Peggy Notebaert Nature Museum in Chicago. “I don't think it's going to be that high everywhere, but there are places where it will be that high. Across the area, it’s going to be at least trillions.”

Periodic cicada. Photo by Allen Lawrance.

There are three species of the 17-year cicadas, which will largely be in Chicagoland and further south. There are four species of the 13-year cicadas, which will emerge north of Chicago. They are all distinctly different from the familiar annual “dog-day cicadas” that emerge in late July and August (and yes, we will have them this year, too).

It’s easy to tell the periodical cicadas apart from our regular cicadas. The 13-year and 17-year cicadas are much smaller, with black bodies, red eyes and orange wing veins. Dog-day cicadas are green and brown with translucent wings. 

Dog-day cicada. Photo by Jobi Petersen Cates.

Plus, periodical cicadas don’t shoo.

“That's a big difference between our regular cicadas and these ones. If you try to approach dog-day cicadas, they fly away, they freak out,” says Lawrance. “These periodical cicadas just sit there. You can pick them up. They can do little alarm calls, but they're not going to run away. It's quite astounding.”

While the periodical cicadas are not as loud, there are so many more of them that the sound seems deafening. The various subspecies sound different, like the scissor-grinder cicada, which sounds a bit like a leaf blower.

“The good news is that you’re going to hear these species more during the midday, winding down by sunset,” Lawrance says. Dog-day cicadas usually call in the evening, although they sometimes sing during the day when skies are overcast. 

If you were here for the 17-year cicadas in 2007, you know where you are about to see them again, since the cicadas will emerge in the same places they did before.

Dead cicadas can still cling to leaves and branches. Photo by Allen Lawrance.

“They generally don’t travel more than 50 meters from where they emerge,” says Lawrance. They breed, lay their eggs and die, and the nymphs tunnel underground to wait another 13 or 17 years. The nymphs of all the species spend a long time underground because they get their nourishment from xylem, the root system of plants that transports water to the stem.

“Xylem is pretty low in nutrients, so they have to process a lot of this fluid in order to gather what they need,” he says. “It takes a long time to get to be a big size that keeps them safe for a little while.”

Protein-rich periodic cicada carcass clinging to a tree. Photo by Allan Lawrance.

The cyclical cicadas should wind down by the end of June—just in time for the dog-day cicadas to emerge. It will be 221 years before the 13-year and 17-year cicadas are again in synch to emerge in Chicago.