If you happened to be looking up at the sky on Tuesday night around California’s San Gabriel Mountains, you might have noticed a strange phenomenon. No, it wasn’t a giant cloud front moving in — it was a “bloom” of ladybugs gliding through the air, and at first, it was quite confusing to weather forecasters.

Mark Moede, a forecaster with the National Weather Service, said, “The radar was showing there was something out there. We looked at the satellite image but there weren’t clouds that size in the area.” After a bit of investigation, it was discovered that the phenomenon was actually a giant group of ladybugs, called a “bloom,” moving across the sky. “It’s an annual bloom that happens around this time of year,” he said.

The bloom appeared on weather screens as 80 miles long and wide, and was flying at 5,000 feet above the ground.

Casey Oswant, San Diego weather service meteorologist, told The Desert Sun that there weren’t many clouds in the area during that time, so the radar activity was curious. “This radar return was much larger than what those clouds could’ve been producing,” he said.

The bloom covered an area of over 1,000 square miles in total as it moved south across California, and though the bloom might be an annual event, this year’s ladybug population was particularly high.

H/T: SF Gate