Moving in clouds, splattering windshields by the hundreds and lighting on anything solid, Minnesota's butterflies are thriving this summer.
Entomologists and county extension agents aren't exactly sure why, but they've all seen a marked increase in the number of butterflies around the state.
"I've never seen anything like it," Dave Schwartz, the Meeker County extension educator, said of the situation in central Minnesota. To the north in Bemidji, extension educator Clark Montgomery has also seen "a significant explosion" of butterflies in the area.
University of Minnesota entomologist Jeff Hahn said unseasonably warm weather may explain the increase, and the wet spring may have hurt butterflies' predators. It may be that an unusually large number of butterflies made it through the winter, or more than usual migrated from Mexico.
"I am not sure anyone knows the exact reason why," Hahn said.
Four species account for most of the shimmering fog of insects that have impressed people at county fairs and along back roads: painted ladies, red admirals, alfalfa and sulfur butterflies.
Painted ladies look like an orange-and-black monarch butterfly, but are about two-thirds the size and have white spots near their wings. Hahn said they are found throughout the state.
The red admiral has similar colors and, he said, are found mostly in the Twin Cities area.
To the west and southwest, there are orange-and-yellow alfalfa butterflies and lemon-yellow sulfurs, Hahn said.
Most people find the butterflies beautiful, but they can also be hard on machinery and some farmers worry about the bugs munching their crops.
"Every car has got it in the radiator or the headlight or something," said Gerald Schwartz of Atwater, agronomy branch manager at Central Lakes Cooperative.
He said he's gotten about a dozen calls from farmers about the butterflies. "We have insect questions maybe once or twice in a normal year," Schwartz said.
Mark Abrahamson, plant pest survey coordinator for the Minnesota Department of Agriculture, said it's hard to tell whether the butterflies are hurting crops.
"We may see some larval feeding from those butterflies when their offspring hatch yet this year," he said. "But it may or may not be significant."
Brainerd Dispatch ©2013. All Rights Reserved.