Is there anything quite as enchanting as a monarch butterfly floating by on a breezy summer day? Surely, most will agree that the monarch (Danaus plexippus) is the queen of butterflies; after all, is that not what her name implies, monarch? Monarch butterflies are known for their long migration to Mexico, but they are only one of at least 17 butterflies and skippers in North America that migrate. However, monarch butterflies are the only butterflies that migrate both north and south in the same generation.
Let me explain. Butterflies such as the clouded skipper, painted lady, common buckeye, dwarf yellow, fiery skipper, gulf fritillary, long-tailed skipper, the question mark and others, migrate usually in a one-way trip. All of these butterflies have multiple generations in one season. Once the butterflies arrive in their southern location they lay eggs. In the spring, the eggs hatch, go through metamorphosis, and it is this next generation that makes the return trip north.
Monarch butterflies on the other hand can have four generations in one summer. The first three generations will have life spans from 2 - 6 weeks and the new butterflies continually fly northward. The fourth generation is different and can live up to nine months. These are the butterflies that will migrate in July and August south for the winter to either Mexico or southern California. The monarchs on the east side of the Rocky Mountains will migrate to Mexico, and the monarchs on the west side will migrate to southern California.
There are several threats to monarch butterflies, one is the weather. If it is dry, monarchs can actually survive below freezing temperatures; but, if they get wet and the temperature drops they will freeze to death. Hundreds of millions of monarchs overwinter in a small area in the Sierra Nevada mountains in Mexico during the winter. A cold snap there is devastating.
Additionally, the overwintering places in Mexico are quickly dwindling. The forests where the monarchs gather are being logged. In 1986, realizing the world treasure they held, the Mexican government created the Monarch Butterfly Biosphere Reserve, which protects 62 square miles of forests in the Sierra Madres where monarchs gather each year and expanded it to include an additional 217 square miles. The reserve has been designated as a World Heritage Site by the United Nations. Several local organizations are working together to stop the illegal harvesting of trees on the reserve to protect the wintering habitat.
What can you do locally to help the monarch butterflies? Plant milkweed! Milkweed is the only food that monarch caterpillars eat! The loss of open spaces with milkweed is yet another reason for the decline of our ever-favorite butterfly.
If you want to see more monarch butterflies in your backyard, plant the bright orange, native butterfly weed (Asclepias tuberosa); this is not the same thing as the tall, purple and pink butterfly bush. Butterfly weed will attract hundreds of butterflies to your yard and provide adult butterflies with healthy food.