What do Virginia, Pennsylvania, Indiana, and Ohio all have in common? Epic swarms of dragonflies, among other things.

WSLS-TV reports that this week, weather radar registered what might first appear to be late summer rain showers. Instead, the green blotches turned out to be swarms of dragonflies—possibly green darners, a type of dragonfly that migrates south during the fall.

Norman Johnson, a professor of entomology at The Ohio State University, told CNN that although these swarms happen occasionally, they’re definitely not a regular occurrence. He thinks the dragonflies, which usually prefer to travel alone, may form packs based on certain weather conditions. If that sounds vague, it’s because it is: Johnson said that entomologists haven’t worked out all the details when it comes to dragonfly migration. They do know that the airborne insects cover an average of eight miles per day, while some overachievers can fly as far as 86.

Based on the radar footage shared by the National Weather Service’s Cleveland Office, the dragonfly clouds seem almost menacing. But, while swarms of any insect species aren’t exactly delightful, these creatures are both harmless and surprisingly beautiful, at least up close. Anna Barnett, a resident of Jeromesville, Ohio, even told CNN that witnessing the natural phenomenon was “amazing!”

Amazing as it may be to see, it’s hard to hear news about unpredictable animal behavior without wondering if it’s related in some way to Earth’s rising temperatures. After all, climate change has already affected wasps in Alabama, polar bears in Russia, and no doubt countless other animal species around the world.

[h/t WSLW-TV]