Bugs like birds have a lot of ways to survive the winter. Monarch Butterflies actually migrate south. The first Monarch you see in the spring may be the grandchild of the last Monarch you saw in the fall.
The black and orange Monarch Butterfly is one of the easiest butterflies to recognize in Michigan. They actually start out from an egg about the size of a sesame seed. Females lay the eggs under the milkweed plants. The eggs hatch 4 to 10 days later depending on the temperature. Tiny little larva or caterpillars emerge and begin eating milkweed. The more they eat the more they grow but instead of their skin stretching like ours, when it gets too tight, they shed the old skin like a shell. The Monarch caterpillar will go through this molting process about four times. When fully grown the yellow, black and white striped caterpillar will be about two inches long.
Next the grown caterpillar attaches itself head down by a dot of silk, sheds its skin for the last time and over the next couple of hours forms into a chrysalis. Green like a leaf, the pupa transforms itself in two weeks into a butterfly and emerges from the chrysalis.
Monarch Butterflies drink nectar from flowers and produce 3-4 broods of offspring per year. After about two weeks they die except for the last generation of Monarchs that hatch in September or October. These special butterflies migrate thousands of miles to their winter grounds in Mexico and live 6-9 months. When the weather begins to change these butterflies start to fly north, mate, and lay eggs. During spring migration north, a female monarch leaves a trail of eggs behind her as she travels. The eggs will become adult butterflies and complete the migration to Michigan later in the spring. They will be the offspring of the monarchs that spent the winter in Mexico.
According to the Journey North website, early-bird butterflies are heading north now, and soon millions of monarchs will leave Michoacán en masse. Mexico's dry season is one of the pressures that forces butterfly colony break-up. Monarchs must have water, and their habitat is bone dry.
Spring is a critical time for monarchs. Their numbers are at their lowest point at this time of year. The old generation is dying. A new generation must grow and survive. You can track their migration on the
Monarch Butterfly Migration Map.
To learn more go to Journey North's Monarch Butterfly Booklets and Slideshows
http://www.learner.org/jnorth/tm/monarch/jr/BookletList.html
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Sunday, March 6, 2011
Image via Wikipedia
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