Imagine a monarch butterfly searching for nectar or a mate in a meadow on a humid afternoon in July. Suddenly, a fast-moving thunderstorm approaches, bringing gusty winds and large raindrops. For the monarch and other butterflies this is not a trivial matter. An average monarch weighs roughly 500 milligrams; large raindrops have a mass of 70 milligrams or more. A raindrop this size striking a monarch would be equivalent to you or I being pelted by water balloons with twice the mass of bowling balls….” (Scientific American)