Monarch (Danaus plexippus)
Nominated to be the United States national insect, the monarch is without a doubt the most familar, recognizable and beloved North American butterfly. Common throughout the entire U.S. and much of southern Canada, the monarch is a frequent garden visitor and is extremely fond of colorful, nectar-rich flowers. The monarch's larvae feed almost exclusively on poisonous milkweed plants. From this highly specialized diet, the caterpillars accumulate milkweed toxins and these secondary plant chemicals are retained in the adult butterflies, rendering them extremely distastful to predators. The attractive bright royal orange and black coloration of the monarch advertises this unpalatability in dramatic fashion. The monarch is one of only three species of “milkweed” butterflies in the U.S. The other two are the viceroy and the queen, and they also are unpalatable to predators and have similar color patterns, thus reinforcing the image of bad-tasting butterflies to would-be predators.
The annual mass migration of monarch butterfies is one of most impressive natural events of any species on Earth. Each fall, hundreds of millions of monarchs from Canada and the eastern United States fly south (a journey that may span 2,000 miles) to the state of Michoacan in central Mexico. Once there, they form dense aggregations within the insulated safety of the mountainous fir forests. From November to March, they overwinter in virtual inactivity on the trunks and branches of trees, surviving on fat reserves and moving only occasionally to obtain water. By mid-March, it is time to leave. The winter survivors mate and begin their trip northward, laying eggs in southern Texas. In turn, their offspring mate and move even farther northward. There is a gradual stepwise progression of monarch generations all the way to Canada. A bountiful new year of monarchs has begun!
The viceroy, monarch and queen are all mahogany brown or orange with black wing veins and white spots, but the viceroy is the only one with a black band across the middle of the hind wings; the monarch has bold black veins on all four wings; and the queen lacks black veins on the front wings, and its white spots are much more obvious.