Suburban homeowners ripping out thirsty lawns are dotting their new drought-tolerant landscapes with milkweed native to California's deserts and chaparral - plants that have the potential to help save water and monarchs at the same time, because the female monarch will only lay her eggs on milkweed.

Overall numbers of the majestic black-and-orange butterflies have dropped from 1 billion to fewer than 60 million over the past two decades as milkweed nationwide has fallen prey to development and pesticides.