On any given day at the National Butterfly Center in Mission, Texas, visitors can to see more than 60 varieties of butterflies. In the spring and fall, monarchsand other species can blanket the center’s 100 acres of subtropical bushlands that extend from the visitor center to to the banks of the Rio Grande river, where their property, and US sovereignty, ends. “It’s like something from Fantasia,” said the center’s director, Marianna Wright.