Flowers have maintained a partnership with insect pollinators from the beginning. They are masters at attracting these love messengers and perpetuating the species through pollination. They use countless ways to accomplish this goal.
For years the so called Corn Belt
has been our breadbasket, as well as that of the monarch butterfly. Despite
farmers' efforts to remove all weeds, common milkweeds proved well adapted to
corn fields and prospered year after year, encouraged, rather than hindered by
annual plowing. Other milkweeds, with different habitat demands lost ground to
the point of becoming endangered. But common milkweed (Asclepias syriaca) and
its rich accompanying fauna, including the monarch butterfly, continued to do
Recently this changed with the advent of genetic
modifications that make corn and other crops resistant to weed killers called
glyphosates, mainly Roundup. Nowadays, approximately 90% of corn and soy seeds
are genetically modified. Now farmers can use Roundup freely on these resistant
crops. This radical change in farming practices is having unpredictable impacts
in ecosystems. One effect of herbicides used in this manner is that it finally
became possible to wipe out populations of common milkweed that previously had
managed to prosper in cultivated fields and along field edges. What is good for the
farmers may prove devastating for the monarchs.
According to some recent studies, most of the monarchs in Canada and the East Coast (fourth and fifth
generations) are descended from the ones born in the Corn
Belt (second and third generations). It seems that the weakest
link in the chain is the Midwest where
herbicide-resistant crops plus herbicides are decimating the common milkweed.
Trying to strengthen the other links may be futile.
Monarchs used to be
numerous in Cape May, NJ,
during fall migration,
but no more despite abundant nectar
Our milkweeds and nectar plants, here in the East, are
almost devoid of monarch butterflies. The same thing applies to the oyamel
forests of Mexico
where overwintering monarchs used only a small fraction of the available
habitat last year (2012).
Common milkweed patch in Southeastern Pennsylvania