WASHINGTON, Feb. 25 (UPI) -- Conservationists say they want tougher rules limiting the use of a common weed killer to save America's dwindling population of monarch butterflies.
The Natural Resources Defense Council, in a petition to the Environmental Protection Agency, said current levels of use of glyphosate -- first marketed under the brand name Roundup -- are wiping out milkweed, the only plant upon which monarch caterpillars feed.