On Saturday, 9/19, I was
witness to a miracle that occurs twice every year!
Monarch butterflies on a Common Milkweed plant (photo: Gay Schroer)
Every year—usually during March in the spring and the last week or two of September—the Monarch butterflies migrate through our
yard. This miracle of nature never
ceases to amaze me. Now I’m not
talking about the 3 or 4 Monarchs you may see feeding or resting in your flower
garden during the summer months.
These migrating Monarchs are already three or four generations removed
from those summer butterflies. The
summer Monarch generations have a short adult lifespan—only three to five
weeks, compared to eight to nine months for the migrators, or the so called super generation.
In the spring of the year,
usually during the second week of March, clouds of Monarch butterflies migrate
from their wintering grounds in the mountains of Mexico to various locations in
North America as far north as Canada.
This generation of Monarchs has already survived a long southward flight
in the fall. They have evaded a
host of dangers, including predatory birds and vehicle collisions, storms,
winds and cold. Those that reach
their wintering grounds in Mexico are the only Monarchs left that can produce a
new generation.
As they pursue their
migration path north and eastward in the spring they seek out the milkweed
plants necessary to the survival of their species, upon which they lay their eggs, recolonizing the southern United States
before they die. Soon these eggs
hatch and the emerging caterpillars feed on the milkweed plant, which is so
crucial to their survival. These
caterpillars then metamorphose into the familiar orange and black adults, which
in turn pursue the milkweed ever northward as winter loses its grip on the
land. They in turn lay their eggs,
etc., etc., continuing this life cycle throughout the summer.
Before the summer’s end there are once again millions of Monarchs
inhabiting the northern U.S. and southern
Canada.
When the late Summer and
early Fall generation emerges they are biologically and behaviorly different
from their summer ancestors. The
shorter days and cooler temperatures trigger changes. Even though these “migrators” look like
the summer adults, they won’t mate or lay eggs until the following spring when
their generation has left the mountains of Mexico. These are the Monarchs that migrate through my St. Peters,
Missouri, yard each late summer and early autumn.
At first you may ask,
“What’s so great about that? Other
animals migrate.” But stop to
think—this is a creature that weighs less than a paper clip and is as fragile
as a piece of tissue paper; yet it survives a journey of thousands of miles
against huge odds. This is not even the
creature that made the original journey.
It is several generations removed from that original Monarch. How did it know to find it’s final
destination—right down to the same specific tree that it’s ancestor rested upon in Mexico several generations ago? How does
it know, each year, to rest for a night in one particular pin oak tree in my
back yard—even though there are dozens of trees of the same species in my yard
and surrounding yards? To
learn more about the amazing Monarch Butterfly and its life cycle Click Here.
Butterfly Weed, with its striking orange blossoms, attracts other creatures as well as Monarchs (photo: Gay Schroer)
I consider this creature a
true miracle of nature—but there is a problem. As we humans spread out more and more into the suburbs and the surrounding countryside, we
destroy the natural growing habitat for the milkweed plant. In addition, as more and more land is
cleared for agriculture, shopping malls, parking lots and other accoutrements
of civilization we rely on herbicides to keep the “weeds” down. There is less and less milkweed to
nurture the Monarchs. In recent
years scientists who study the Monarchs have noted an alarming decrease in
their populations.
What can I do, you may
ask? We as individuals may not be
able to solve the whole problem, but we can help by growing milkweed in our
gardens. If every gardener
nurtured a small patch of milkweed it would give this valiant little flyer a
place to lay eggs for the next generation. Milkweed is a sun loving plant, so
shade gardens are not to its liking.
However, my husband grows Butterfly Weed in a pot on the deck of our
Ozarks cabin, and each year it draws dozens of Monarchs to its bright orange
flowers.
To learn more about growing milkweed in your garden Click Here. Even though common milkweed presents a
containment problem in the garden, this website offers several tips on
containment measures. It also gives information on other forms of
milkweed—most notably, Butterfly Weed, which is a very striking plant if your
garden has a suitable site for it.
Submitted by Gay Schroer,
World Bird Sanctuary Volunteer/Photographer
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