Over the past couple of decades, monarch butterflies, one of the most recognizable (and important) visitors to gardens across North America, have been declining in number–as much as 95 percent of the population has disappeared since the 1980s. The reasons are numerous: Mexico, where the pollinators migrate to escape harsh winters, has eliminated many of the trees where monarchs flock and severe and unpredictable weather due to climate change has disrupted populations.