Populations of monarchs have decreased significantly in the past two decades, from an estimated 1 billion butterflies in 1995 to about 34 million today. The Obama administration has set a goal of boosting the eastern population of monarchs back up to 225 million by 2020.

Milkweed is the only plant on which monarch butterflies will lay their eggs, and monarchs must reproduce along their migratory path to survive as a species. The monarch’s journey to and from Mexico takes three to four generations. They fly south from eastern North America to roosting spots in the mountains of central Mexico, where they spend the winter before heading back to lay eggs on milkweed plants.

In many areas of the Midwest and southern Great Plains, farmers and landowners have cleaned milkweed and other weeds from along fence rows, pasture land, cropland and buffer areas along waterways and wetlands. Those weeds included many of the flowering plants that provide monarchs and other pollinating insects with shelter and food.

"We're trying to add milkweed back into the landscape, but also other flowering plants," Zezula said.

The 10 states where the USDA will spend the funds, providing technical and financial aid for landowners who plant for monarchs, are:

  • Illinois
  • Indiana
  • Iowa
  • Kansas
  • Minnesota
  • Missouri
  • Ohio
  • Oklahoma
  • Texas
  • Wisconsin

The Associated Press contributed to this report.