Schoolchildren and seniors are pushing to undo an ecological catastrophe threatening monarch butterflies — by planting the milkweed that monarchs need.

The dwindling of migrating monarchs has been so swift that federal scientists say farmers, utilities, homeowners and public-land managers also must get involved. U.S. Fish and Wildlife Service officials estimate monarchs have declined by about 95 percent since 1996, to 33 million from 1 billion.

"We were hoping to see one or two monarchs this year. We didn't see any," said teacher Allison Cole at Flagstaff Academy in Longmont, one of several Colorado schools where students have planted milkweed gardens.

An emerging national strategy calls for creating milkweed safe havens and butterfly "highways" for the orange-black-and-white monarchs.

While monarchs draw nectar from many flowers before laying eggs, their caterpillars can survive only on milkweed. Monarchs' 3,000-mile migration from Canada through the United States to wintering sites in Mexico requires multiple generations of butterflies because each can fly only about 100 miles.

The butterflies are victims of prairie conversion and increasing use of glyphosate herbicides. These herbicides, sprayed on crops genetically modified to withstand them, kill other plants, including the milkweed that once served as habitat for pollinators such as butterflies, bats and bees.