Monarch Butterfly

Scientific Name: Danaus plexippus
Common Name: Monarch Butterfly

Monarch Butterfly - photo by Bob Suchanek August is the best month to see Monarchs in Minnesota. Did you know that this is the only butterfly in North America that actually migrates in the fall to a warmer climate? That's what makes it unique among all the butterflies in Minnesota.

The Monarch is a beautiful butterfly. But did you know that the markings on most butterflies are there to scare off predators -- specifically birds? The bright orange and black markings on the Monarch tells birds and other "would-be Monarch eaters" that the Monarch is poisonous. Do you know what makes them poisonous? It's what they eat -- milkweed. The milkweed contains a chemical that birds can't stand.

Monarchs are totally dependent on milkweed when they are in the larval stage. The most common milkweed species in Minnesota is, you guessed it, the Common Milkweed or Asclepias syriaca. All monarch eggs are laid only on milkweed plants. After the newly hatched Monarch larvae eat the egg they were laid in, the young caterpillars start eating the milkweed leaves. Monarch caterpillars eat like crazy until they grow about two-inches long. They even shed their skin (molt) up to four times while they're growing!

Adult Monarch butterflies eat nectar from flowers. Flower nectar consists of about 20% sugar, which gives the Monarchs energy. Flowers that have lots of nectar are, of course, what Monarchs prefer. But you'll see them land on all kinds of flowers to take a sip. Monarch butterflies find flowers by sight, but they decide if its worth eating through taste receptors that are on their feet! They suck up the nectar through a long tube-like mouth.

Like all butterflies, Monarchs aren't born with wings. They actually go through four very different stages in their lives:

  1. Mom lays the egg. One female Monarch can lay up to 400 eggs.
  2. In a couple of days, the egg hatches and turn into a caterpillar with black, yellow and white stripes. A Monarch caterpillar can get kinda' fat and grow about two-inches long.
  3. Caterpillar makes a "house" called a chrysalis that is attached to a leaf or twig. The caterpillar makes this stuff that looks like silk and uses it to build the chrysalis. It attaches the base of the chrysalis to a sheltered spot under a leaf or twig and then hangs upside down in it for about five days. Inside the chrysalis, the caterpillar turns into a pupa. The chrysalis is really neat looking -- it has a shiny, light green color with a gold band near the top. The gold is iridescent looking. In the chrysalis, the pupa is going through some major physical changes.
  4. Butterfly breaks out of the chrysalis and is free to fly around and do what butterflies do.

The four stages take about a month to complete. During an average Minnesota summer, this whole process can happen three or four times. This means that there can be three to four generations of Monarchs born in one summer. Most Monarch butterflies only live a few weeks -- long enough to breed and lay eggs to start the cycle all over again.

So if you think the metamorphosis was cool, just wait 'till you hear the next part. The last generation of Monarchs born during the summer are different. These are usually born in late August when the days get short and the temperatures start cooling down a bit. These changes prevent the Monarch butterflies from maturing enough to reproduce, so they live for about eight to nine months.

Map of Monarch Migration from Minnesota to MexicoBut, have you every seen a Monarch butterfly in the winter in Minnesota? Of course not! So where did they go? They fly all the way down to Mexico to hang out during the winter! That's a long trip for Minnesota-born Monarchs -- about 3,000 miles! Monarchs use the same route to go to the same place every winter. This place is in the Sierra Madre mountains west of Mexico City, Mexico.

By now you're probably thinking, hey, Monarchs are just bugs! They can't read maps, so how do they know how to get to the exact same spot every fall? Scientists think that Monarchs use the position of the sun to tell them when to head for Mexico and how to get there. They think they also use Earth's magnetic field to help them figure out where to go.

Before the migration begins, you can often see Monarchs in groups of five or more as they start their way south. But, there are some spots where lots more Monarchs get together before they start migrating.

Monarch ButterflyWe all know that Monarchs can't fly very fast. So how do they travel all the way to Mexico? They use the natural air currents and thermals that are way up in the sky to get them to Mexico faster.

When they get to Mexico, they hang out in huge numbers in forested areas. There are numerous sites in the Sierra Madre mountains where the Monarchs like to stay. But, in spite of efforts to protect them, many of these sites are being logged or damaged by people. When the damage is severe, the Monarchs don't have any place to stay.

The Monarchs that survive the winter in Mexico start migrating back to the U.S. in the spring. They mate all along the way and find milkweed on which to lay eggs. These eggs hatch, and eventually turn into butterflies that continue migrating north. Monarchs are found all the way up into Canada.

You can help protect Monarchs in Minnesota by planting a butterfly garden in your backyard. Plant flowers that give Monarchs food and be sure to include some milkweed!

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