An unusually large number of dragonflies have been spotted in Wisconsin this summer.
"They were just swarming all over," resident Corrine Ollis said. "I would say they were hummingbird size. They weren't as thick as a flock of birds, but there were thousands of them."
Ecologists have attributed the phenomenon to the higher amounts of rainfall that have fallen across the country.
"Most of our flooding and heavy rains usually occur earlier in the spring or summer like May or June, which is early for the dragonflies to emerge," said Mary Holleback, director of Riveredge Nature Center. "But the flooding happened at the end of July and early August when they were emerging. It makes sense that we just timed the dragonfly hatch to go along with the influx of mosquitoes this year."
More rain means more standing water. That, in turn, leads to a boom of mosquitoes - something dragonflies love to feast on.
"The ones that people are seeing in large numbers right now are called the green darner," The Milwaukee Public Museum's Dr. Susan Borkin told the Wisconsin Journal Sentinel. "They're warm-blooded animals, and so the warm temperatures allow them to develop much faster than they might be under cool conditions."
Once cooler weather moves in, the dragonflies will start to migrate south where the weather is warmer.