A Monarch butterfly on the flowers of a milkweed plant (Credit: Mark Rogovin/The Field Museum)

In the past two decades, the monarch butterfly population east of the Rocky Mountains has declined by 87 percent. That’s due in part to the fact that the only plant that monarchs lay their eggs on – milkweed – has become scarcer thanks to farmers removing it from their fields. Scientists say that stopping the monarch’s decline will require planting some 1.8 billion stems of milkweed. And, according