John Maresh was driving west on Interstate 10 on a clear day in October 2016 when he ran into monarch butterflies. Literally.Along the 35-mile stretch between Sonora and Ozona, a “river of monarchs” was flying across the highway at windshield height. Maresh veered a bit in an attempt to miss one butterfly and ended up smashing two others. “It was disconcerting,” he says. “Other cars were hitting as many as we were.”But Maresh wasn’t just a random driver. As an environmental project planner with the Texas Department of Transportation, he studies the impact of transportation on native species. So he immediately had questions. Is this normal? Does this happen every year? Is it worse in some areas?As it turns out, someone else in Texas was…