Trillions of cicadas last seen when Thomas Jefferson was president to swarm US for first time in more than 200 years

Prepare yourself for an exciting ride! This year will be historic because it will be the first time in more than 200 years that the two different cicada broods, XIX and XIII, will emerge from the earth simultaneously. Imagine that this won’t occur again until 2244, and the last time it did so was during the presidency of Thomas Jefferson!

These inch-and-a-half-long insects have remarkable bodies with strong, multifaceted eyes that are a bright red, and delicate, transparent wings that extend to almost three inches. The Environmental Protection Agency tells us that cicadas are not dangerous to people, pets, gardens, or farms, so don’t be fooled by their appearance.

In actuality, birds and mammals rely heavily on these amazing creatures as food. As they break down, they even add nutrients, improve water filtration, and aerate lawns, all of which contribute to healthy soil.

The majority of cicada species come out once a year, but two unique broods that live underground for 13 or 17 years are found in the United States.

“The co-emergence of any two broods of different cycles is rare, because the cycles are both prime numbers,” John Cooley, a cicada expert at UConn explained.

“Any given 13 and 17-year broods will only co-emerge once every 13 x 17 = 221 years,” Cooley added.

Known for its 17-year cycle, Brood XIII is found mostly in the northern Illinois, eastern Iowa, southern Wisconsin, and some counties in northwest Indiana.

With a slightly shorter 13-year cycle, Brood XIX covers a larger area, encompassing 15 states such as Georgia, Virginia, Alabama, and Arkansas.

These two broods only cross paths significantly in a small area of central Illinois and occasionally in Indiana, despite their territories encompassing parts of 17 states. In fact, there may be some interbreeding between broods due to their close proximity.

Small tree branches are slitted by female cicadas, who then deposit clutches of 20 to 30 eggs inside of them. Throughout her life, a single female can lay hundreds of eggs! The young cicadas emerge from these eggs in late summer and dig themselves back under.

John Cooley draws attention to how unusual this occurrence is by drawing a comparison to something even more amazing than Halley’s Comet. “This summer, some will get a chance to witness a phenomenon rarer, and probably louder, than Halley’s comet,” he said.

“You cannot possibly be unaware that periodical cicadas are out, because they’re out by the millions and millions, and they’re noisy, charismatic, active insects that are just everywhere,” Cooley noted.

But because they lay their eggs in tree branches, cicadas can be dangerous to young trees, according to the EPA. The organization advises using netting or mesh to cover susceptible saplings in order to keep these hardworking insects away.