Home > Great Big Greenhouse Blog > August 2015 > BONNIE'S GARDEN--Monarchs


Monarch butterflies have certainly been in the news a lot over the past couple of years.  This is probably one of the most recognized butterflies in the world—with their showy orange and black-striped wings.  Monarchs have a very interesting life cycle.  Monarchs usually lay one single egg at the base of a milkweed leaf near the top of the plant.  The eggs hatch after just four days.  The caterpillar starts off by eating its shell casing, then goes on to eat the leaves of the plant.  They will only eat milkweed leaves. 

The caterpillar only spends about two weeks as a caterpillar, during which it will increase its’ size about 2000 times,  before it then builds a chrysalis and pupates for another 10 to 14 days before hatching as a butterfly.  Once they hatch, their main job is to reproduce.  

Each year, staring in spring, we get about three to four generations of Monarchs for the summer.  The fourth and final generation of monarchs, which hatches in early fall, will migrate to where they will over-winter.  Our eastern U.S. Monarchs will migrate to Central Mexico where they will spend the winter in oxamel fir trees on the south-facing slopes of the mountains.  Monarchs west of the Rocky Mountains will migrate to California where they will spend the winter in eucalyptus trees.

The first Monarchs we see in the spring are usually hatched from eggs laid by females who overwintered in Mexico.  The butterflies will migrate north and begin laying eggs in the southern-most U.S.  The eggs hatch, caterpillars grow, pupate, hatch as adults, mate, lay eggs and die—living only five to eight weeks total. 

The last generation that hatches in the fall is biologically different from the previous three generations.  When they hatch from the chrysalis, their reproductive organs are not yet able to reproduce.  These are the adults that will migrate to Central Mexico where they will over-winter in a state similar to hibernation.  Every year, this fourth generation will go to the same place--even the same trees.  In the spring, they will migrate north, their reproductive organs mature now, laying eggs along the way.  This fourth generation will live up to eight months.

The Monarch’s caterpillars can only eat milkweed leaves.  Because of mass destruction of milkweed, it’s dramatically affected the Monarch population which is estimated to have declined by as much as 90% in the past twenty years.  Next week:  how we can help by incorporating milkweed into our perennial beds.
Posted: 8/11/2015 by Bonnie Pega | with 0 comment(s)
Filed under: Bonnie's, butterflies, Garden, Monarch
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