Cicadas return to Baton Rouge after 13 years in dormancy

Cicadas — winged insects that make up in noise what they lack in longevity — have returned to Baton Rouge after their 13-year dormancy. This time, researchers would like you to be their eyes and ears.

LSU instructor Barry Aronhime and his Biology 4254 ecology lab students are participating in research with other universities seeking more understanding of these boisterous bugs, whose emergence brings a cacophonous courtship that lasts for about a month.

The brood of periodical cicadas that stretches along the Mississippi River roughly from Baton Rouge to Vicksburg, Mississippi, began reappearing early this month — a little later than usual because of a colder and longer than normal winter.

And when they show up, they show up in a big way.

“They have a safety-in-numbers strategy for survival,” said Chris Simon, professor of ecology and evolutionary biology at the University of Connecticut, who came here to study this year’s emergence. “They don’t run away from predators readily. They’re easy to catch. They’re obvious, bright colors. They just rely on their numbers to survive, so when the numbers drop too low they can get wiped out. Their mating behavior also depends on having these big numbers. If they don’t have these big numbers, they don’t mate very well.”

When they mate very well, people are likely to notice.

Male cicadas emit a distinctive mating song to attract females after they’ve burrowed up from the ground and shed their nymphal skins. Actually, there are three species of cicadas in the brood, and each has its own call that entices females only from that species. They mate, then the females lay eggs in trees, and the adults die. The eggs hatch, and those that emerge burrow into the ground, slowly growing until the cycle resumes.

That happens at various times all over the eastern U.S., with some broods operating on 13-year cycles, others on 17-year cycles.

To study the size and geographic sweep of this brood’s emergence, schools cooperating in the project are turning to crowd-sourcing.

People who see cicadas may report their location online at magicicada.org/report/report.php. The sightings will be posted on a map at magicicada.org/databases/magicicada/map.html.

“In the past, all of our mapping was done by a couple of people driving around in cars, writing postcards to all the county agents, phoning them up, getting addresses and names of people and driving to them,” Simon said. “It was very tedious. We didn’t have really detailed maps, because one or two people couldn’t cover the entire distribution. But, using the general public, we can now cover a wider range.”

In addition to learning about the size of this brood, Researchers also hope to get permission from some landowners to study the cicadas through their entire life cycle, digging up where the nymphs have burrowed to monitor how they develop.

“We have lots of measurements of how fast they grow up north,” Simon said. “We have some in Oklahoma. We have a lot in the Midwest, but none in the Deep South, where it’s so much warmer. We’re trying to understand how fast they grow.”

Aronhime said it’s also giving students hands-on experience.

“Here, they get to do a real project that is real science,” Aronhime said. “That’s something that can be a unique experience for an undergraduate, to be able to do real research. It’s also nice that we get to collaborate with other universities.”