Meet Danaus
plexippus – the Monarch butterfly – in larval stage.
click on image to enlarge
This fella is posing on one of the many, many milkweed
plants found here at The Platz.
Adult butterflies feed on the nectar of flowers but in
its larval stage of life the monarch feeds exclusively on milkweed. This endows it with a unique defense
mechanism. The monarch is poisonous to
predators as a consequence of dining upon milkweed. Toxic chemicals found in milkweed build-up
and remain in the critter even after it metamorphoses into a butterfly giving
it a chemical defense system.
Remarkable!
This caterpillar will form a chrysalis from which an
adult butterfly will emerge. The entire
process of egg, caterpillar, chrysalis, and butterfly takes about four weeks
with multiple generations born over the course of a year.
This insect is even more remarkable when you consider its
travels. Monarchs migrate up to several
thousand miles from Mexico to Canada and back.
Beginning in the spring migrating females head north in relays laying
their eggs along the way with new generations of butterflies replacing the
old. Each butterfly will migrate once
with its great-grandchildren migrating the following year. The science behind the migration supposes that
the monarchs use the earth’s magnetic field to navigate and the position of the
sun to signal when to depart for Mexico.
Since the butterfly only lives a few weeks it is the last
generation of monarchs born in late summer or early fall that make the migration. As the temperatures begin to fall and the
days grow shorter this generation of butterflies doesn’t mature enough to
reproduce allowing them to live up to eight or nine months. They’ll make the migration south for the
winter and return next year to reproduce.
Monarch numbers are in decline as a consequence of
pesticide and herbicide use and loss of habitat. If you’re inclined to lending a hand plant
milkweed and nectar producing flowers for this amazing animal.
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