CHICAGO (CBS) — They’re creepy. They’re noisy. And they’re coming out early.

Seventeen-year cicadas are emerging in Chicago’s western suburbs. That high-pitched cicada sound is getting louder by the day in places like La Grange.

Trees and homes are covered with the big bugs, and their empty shells are all over sidewalks.

A bug expert from the Peggy Notebaert Nature Museum said this batch of periodical cicadas usually emerge from underground every 17 years, but some are coming out four years early.

The cicadas don’t cause any real damage or hurt plants or gardens.

The rest of this 17-year brood will emerge in 2024, along with the 13-year cicadas.