Monarch butterflies are known for their incredible mass migration, where millions gather together in only a few small areas in California (western population) and Mexico (eastern population) each winter. North American monarchs are the only butterflies that make such a massive journey—upwards of 5000 kilometers! Not bad for an insect that has a wingspan of only 8-10 centimeters.
Monarch butterflies begin life as eggs and hatch as larvae that eat their eggshells and, subsequently, the milkweed plants on which they were placed. Milkweed plants, Asclepias spp., are the host plant of monarch butterflies: they are the only type of plant the larvae can eat. Adult butterflies rely on nectar plants, and will visit many types of flowering plants to get this energy-rich drink.
Unfortunately, due to a variety of factors, monarch populations have drastically declined, and the winter of 2013-2014 had the fewest monarchs in Mexico since records started being kept. But all is not lost: if everyone across their migration route planted milkweed plants and reduced the amount of pesticides being used, we may help bring this butterfly back from the brink.