Butterflies are a wonder of nature. They seem fragile, yet the strongest of them—the Monarch, Danaus plexippus—can fly as far as 4,000 km from Canada to Mexico to survive the winter. But what are these beautiful insects definitely not resistant to? Butterflies, both diurnal and nocturnal, are the first to react to any human actions that disrupt the natural balance of their environment. So, if something starts to go wrong with butterflies, it should be a strong signal for us humans: STOP!