As the cicada double brood event approaches, questions arise about when and where this extraordinary occurrence will take place. Here’s an overview of what to expect from this remarkable natural phenomenon, which unfolds just once every 221 years.
Once hatched, the immature periodical cicadas, known as nymphs, sustain themselves by feeding on tree root sap underground before emerging as adults to engage in mating. This process involves a noisy and frenzied display that spans several weeks.
For the first time in over two centuries, two colossal broods of periodical cicadas, Brood XIII and XIX, are poised to emerge simultaneously in the United States after spending 17 and 13 years underground, respectively. These periodical broods are unique to eastern North America and emerge in massive numbers when they reach adulthood.
The impending emergence of these two broods is an exceedingly rare event, last observed in 1803. This synchronized emergence won’t recur until 2245. Although there are thousands of cicada species, only seven belong to the periodical cicada genus (Magicicada), with three having 17-year life cycles and four with 13-year cycles.
When will the cicadas begin to emerge? According to data from the Periodical Cicada Project database at the University of Connecticut (UConn), the double brood is expected to emerge in late April 2024 and persist for several weeks.
The sheer number of cicadas expected to emerge is staggering, with estimates ranging into the trillions across 17 states. Despite this immense volume, the simultaneous emergence of Brood XIII and XIX is not anticipated to differ significantly from other periodical cicada emergences, primarily because they typically emerge from different locations. There’s only a small area in Springfield, Illinois, where the two broods might co-emerge.
Why is this event so rare? The rarity stems from the infrequent overlap of specific periodical broods with different life cycles in terms of timing and location. The co-emergence of broods with distinct cycles occurs only once every 221 years due to the prime-numbered intervals of their life cycles.
Areas expected to be affected by the double brood emergence include the Midwest, particularly around north-central Illinois, Ohio, and Iowa for Brood XIII, while Brood XIX will extend to parts of Illinois and a broader geographic region in the southeastern US, encompassing states like Louisiana, Virginia, and North Carolina.
Concerning interbreeding between the two broods, limited overlap between them makes it unlikely. Even if interbreeding were to occur, any resulting offspring would likely be indistinguishable from non-hybrid cicadas. Research indicates extensive interbreeding between 13 and 17-year cicadas of the same lineage, but it hasn’t led to changes in their life cycles.
As for what people can expect to witness, the double brood emergence will resemble a typical periodical cicada emergence, with vast numbers emerging from the ground in the evening. Mornings will see cicadas perched on lower vegetation after shedding their exoskeletons before climbing into trees to mate and lay eggs.
After completing their mating and egg-laying activities, most cicadas will perish within two to six weeks, with many succumbing during the emergence. Despite the risks, some will survive to continue the cycle by laying eggs in trees, which will eventually hatch and lead to a new generation of nymphs burrowing underground.
