National Weather Service meteorologists noticed something puzzling on their radar screens in Southern California on the evening of Tuesday, June 4 — a big green blob, reported NPR.

“It was very strange because it was a relatively clear day and we weren’t really expecting any rain or thunderstorms,” Casey Oswant, a NWS meteorologist in San Diego, tells NPR. “But on our radar, we were seeing something that indicated there was something out there.”

Meteorologists called a weather spotter in Wrightwood, Calif., near the blob’s location in San Bernardino County. Oswant says the spotter told them the mysterious cloud was actually a giant swarm of ladybugs.

The phenomenon is known as a ladybug “bloom,” and while this one appears particularly large, Oswant says it’s not the first time local meteorologists have spotted the beetles.

On the radar, the cloud of insects looked like a “light rainstorm” — not quite the density of a severe thunderstorm, she says. They were flying about a mile above the ground, she said, in the cloud that was about 10 miles wide.

The mass of beetles was spotted heading south just before 9 p.m. on Tuesday night and eventually the weather watchers lost sight of them.

PHOTO: National Weather Service