Periodical cicadas will emerge in 2024. Here's what you need to know about these buzzing bugs.

Periodical cicadas aren't present every spring, but when they do emerge, they come in loud, buzzing hordes. This year, trillions of these beady-eyed bugs are expected to appear in several U.S. states. Here's what you need to know about cicadas.

There are two types of periodical cicadas — ones that come out every 13 years and ones that come out every 17 years. They emerge in broods, which are labeled with Roman numerals.