Emily Chan
Every 221 years, billions of cicadas from two different broods appear in a rare natural event known as dual emergence.
It’s an exciting time for entomologists and bug enthusiasts, but it’s a nightmare for those who get the creepy crawlies from insects.
This spring, the schedule of these broods has aligned for the first time since 1803, and they are set to emerge throughout the Midwest and Southeast regions of the U.S.
The insects belong to two distinct groups of periodical cicadas: Brood XIII and Brood XIX. The first brood surfaces from the ground every 17 years, and the latter materializes every 13 years.
While some cicadas emerge every year, periodical cicadas spend most of their lives underground. They feed off the sap that leaks from tree roots.
When they tunnel to the surface using their front legs, they will begin mating. During the mating process, the males vibrate membranes on the sides of their bodies to create a song that attracts females.
After a pair of cicadas has finished mating, the female will lay their eggs in a slit on a tree branch. Adult periodical cicadas live for three to four weeks and won’t survive long enough to see their eggs hatch. The newly hatched nymphs will burrow down into the ground to repeat the cycle all over again.
The two broods are expected to crop up in separate areas across the Midwest and Southeast in 16 different states, but they will also overlap along a strip of land in northern Illinois and eastern Iowa.
More than 1.5 million cicadas may be buzzing around within an acre of land. They will appear in forested areas and urban green spaces, serving as a food source for birds and benefitting the ecosystem overall.
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