Six states and the Federal Highway Administration have agreed to make the roadsides along Interstate 35 friendlier for bees and butterflies to help the insects boost their declining populations.

The 1,500-mile stretch of road between northern Minnesota and southern Texas is a path for monarch butterflies that migrate between Mexico and Canada. Both the butterflies and bees pollinate plants that produce much of the nation's food.

Officials from Minnesota, Iowa, Missouri, Kansas, Oklahoma and Texas and the federal government signed an agreement Thursday to improve the habitat and develop a branding campaign informally naming the interstate the "Monarch Highway."

Honeybee and monarch butterfly populations have been dwindling in recent years.