Tuesday, September 14, 2010

Endemic: it only happens in one place.

At the beginning of 2nd grade Mrs. Clinger gave us homework: look on ditch banks for milkweed.  It has long, silvery leaves that are three or four inches long.  The leaves are soft to the touch.  We recognized the plant by its seed pods bursting with seeds hanging from silky parachutes.  I broke a leaf, and found a white, milky juice inside from which the plant gets its name.  Once we identified the plant, we were to look for a black, white, and yellow striped caterpillar.  Put the caterpillar in a jar with a milkweed cutting and bring it to school.  In a matter of days each caterpillar hung upside down like a J and a pale green chrysalis formed around him.
At school I checked the chrysalises daily, eagerly awaiting the end of the metamorphosis. Finally, beautiful monarch butterflies crawled out.  We did our best to resist the temptation to touch those beautiful orange and black wings while we waited for them to dry.  I learned the hard way that the butterflies whose wings were touched would never fly.

Butterflies migrate from Mexico all the way to Canada and back--up to nearly 3,000 miles.  This journey occurs over four generations of monarchs in the course of one year since most live only 2-6 weeks.  No one knows how each newly hatched caterpillar-turned-butterfly knows to continue the multi-generation migration.  The monarch I hatched in 2nd grade was the final generation of the year.  It was headed south towards Mexico for the winter. 

Milkweed doesn't look like much.  In fact, it's toxic if you eat much.  But that is what protects the butterflies from predators.  The milkweed chemicals it eats as a caterpillar remain inside and make many of its predators sick.  Milkweed seeds, with their silky parachutes, were used in early colonial days to fill pillows and comforters--their structure is similar to down.  During World War II, when other supplies were short, milkweed pods were collected and used to stuff life jackets for soldiers.
 I thought of these things as I stood by the milkweed in the garden.  I don't see much milkweed anymore.  Building houses, diverting water, and replanting with exotic plants has made milkweed harder to find.  The first seedpod had burst and I reached down to gather the seeds with their weightless white sails.  Milkweed is the only plant that a monarch butterfly will lay its eggs on.  It is the only plant that the caterpillar will feed on before forming a chrysalis.  I held the feathery seeds cupped in both hands and watched the breeze pick one from the top.  It soared above my head and away to the west.  I looked at the city filling the valley below and wondered if the seed will find a place to grow.  The migratory pattern of monarchs is threatened because of habitat loss.  Love a butterfly--grow milkweed.  I lifted my hands up to the sky and let all the seeds fly on the invisible breeze to find a place to wait for spring.

Sources: http://www.monarch-butterfly.com/, http://www.worldwildlife.org/species/finder/monarchbutterflies/monarchbutterflies.html