Daniel Trudeau is a Wave Hill Environmental Educator.
Each fall, millions of Monarch butterflies—the entire North American population—migrate from the United States and Canada south to wintering grounds in central Mexico. This year, a Wave Hill resident is taking part in the journey. For several weeks this fall, the education staff raised Monarch pupae in cages in an attempt to raise a successful contingent of adult butterflies to send southward.
The pupae—voracious striped caterpillars—arrived from a scientific research company in mid-September. For several weeks, we fed them milkweed from the Wave Hill grounds and watched them grow large on the feast. Unfortunately, one by one these 18 caterpillars died off, with one notable exception. In early October, our last remaining pupa climbed to the top of his cage, curled his body into the “J” shape synonymous with butterfly metamorphosis and began to create a gorgeous green and gold chrysalis. The pupa remained in this elegant structure for about two weeks before emerging as a full-fledged Monarch. Before we released our lone survivor, we tagged him with a tracking number— MMZ 126 (aka Manny)—and sent the information to be logged online so researchers who encounter the butterfly on his journey can chart his movements.
The annual Monarch migration is a highly celebrated event, but there’s still a great deal we don’t know about the mechanics of the great journey. Monarchs live for a relatively short time: Four generations are born each summer, three of which die before ever beginning the journey south. As a result, the butterflies that have passed through Wave Hill’s gardens in the last month on their way south are the great-great-grandchildren of the Monarchs that left Mexico last spring.
So how do the insects that emerge from the chrysalis in the fall find their way to a place they’ve never seen? And how do Monarchs from all over the continent end up spending the winter in one relatively small area in central Mexico? Even though we don’t completely understand it, it’s exciting to know that our solitary sojourner is taking part in this beautiful, mysterious journey.
SOURCES: Journey North (http://www.learner.org/jnorth/); Monarch Watch (http://www.MonarchWatch.org)