For the first time since Thomas Jefferson’s presidency, two major cicada broods are expected to emerge in the same year this spring, bringing potentially trillions of these large, awkward-looking insects to the Southeast and Midwest.

Cicada Brood 19 — which emerges every 13 years — and Brood 13 — which emerges every 17 years — are both expected to surface this year. It’s the first time the two broods have overlapped since 1803.

The bugs usually begin to emerge around the end of April or beginning of May, crawling out from underground to reproduce before disappearing again.

“Mainly for Alabama, it’s going to be Brood 19 in central and somewhat northern Alabama,” said entomologist Meredith Shrader at Auburn University. “And it will be millions and millions of these guys coming out, and they’ll be out for about six to eight weeks, and then they’ll die and disappear for another 13 years.”

In Alabama, there are multiple kinds of cicadas. Some emerge every year or two. Some are on the 13-year cycle.

The overlapping super-brood experience in Alabama isn’t expected to be any different from the usual 13-year cycle. Brood 19′s range covers much of the Southeast and Brood 13 is mostly found in the Midwest. There are only a few places, mostly around central Illinois, where the ranges overlap.

But the two broods won’t surface in the same year again for another 221 years — until 2245.

“Everybody’s getting really, really excited,” said Shrader, who is also an insect diagnostician with the Alabama Cooperative Extension System. “Some people are dreading it, but it’ll be fun.”

Multiple species in Alabama

The cicadas that can be seen every year in Alabama are larger, with green bodies and dark eyes. Shrader said these stay underground for around two to five years as they mature before emerging, shedding their exoskeleton and mating. Those cicadas aren’t all on the same schedule, so a handful will come out each year.

“A majority of people are very familiar with the annual cicada and you can see their little exoskeletons stuck on the trunks of trees on the sides of houses,” Shrader said.

Then there are the periodical cicadas, which emerge in massive swarms every 13 or 17 years.

These bugs are darker in color, with red-orange eyes and translucent wings. They can cover the ground when they’re active, and make noise reaching 85-100 decibels when calling in unison.

Shrader said all cicadas live underground in a nymph stage for most of their lives, feeding on nutrients from tree roots. Then, according to their cycle, the insects emerge, usually around the end of April or beginning of May. They shed their exoskeletons, reproduce and die.

Female cicadas lay eggs in small, growing twigs on trees, and the young cicadas burrow underground to start the cycle over again.

Buffet for wildlife

While some might be put off by their appearance or the sheer number of them, Shrader said they’re harmless for people.

“People aren’t used to seeing insects on that scale, and so people might be a little apprehensive about them emerging,” she said. “But, for people, they’re harmless.”

The emergence can benefit birds, mammals, snakes and other animals that can feed on cicadas.

“It’s like a buffet,” Shrader said. “A buffet say that happens every 13 or 17 years.”

Cicadas can damage plants, although Shrader said it’s not usually a severe problem.

“The female will lay eggs in soft, pencil-sized twigs,” Shrader said. “And so that’s where agriculturally, or for ornamental [plants], people that have nurseries, these insects might be a pest.”

If people are concerned about sensitive or delicate plants, Shrader said, they can purchase a bird netting or mesh to try and block the cicadas from laying eggs in the young branches. Insecticides will not be effective against a full swarm of cicadas.

“[A mechanical barrier] is probably the best bet that you could do to prevent them from damaging trees,” she said. “But there’s nothing you can spray on a tree that will prevent them from landing and ovipositing 100%.”

Overall, Shrader recommended that people view the emergence as a unique experience, especially to share with children to learn about the natural ecosystems.

Researchers, she said, will also be studying the phenomenon, especially to see how the two broods interact where they overlap.

“The bug geeks are interested in looking at the different species intermingling,” she said. “They’re going to be looking and seeing if the 17-year cicada will hybridize with the 13-year cicada, and that might cause some synchronization between those two groups. People can nerd out on that aspect of it.”