I have no excuse for not remembering my daughter’s birthday, which is Sept. 18. While waiting in the hospital room for her delivery a couple of decades ago, there was a near constant stream of the orange and black monarch butterflies that would approach the building, climb the additional floors to clear the roof and continue their southward migration to Mexico. Every year since then, when I see the monarch migration beginning, I know that her birthday is rapidly approaching.
Unlike the more familiar bird migrations, monarch migration is a multi-generational endeavor. The butterflies that we see coming back north in Missouri next spring will be the descendants of the ones that are passing through here now. On their way back here next spring, they’ll produce a brood in Texas or Oklahoma and those offspring will be our first monarchs of 2012. Here in Missouri, broods are produced in summer and fall. The life cycle from egg to caterpillar to chrysalis to adult only takes a little over a month to complete. Adults live for only four or five weeks, except for the last generation each year that can live for seven to eight months, reaching Mexico in the fall and coming part of the way back north in the spring.
If you’re spending much time outside, or staring out hospital windows, you have probably observed the recent increasing number of monarchs in the air or visiting flowering plants for nectar. Because monarchs don’t fly at night, a few lucky Missourians may also discover night roosts, where the insects will mass on trees for a night or two of rest before resuming their southward flight.
Along with the autumnal equinox, which is this Friday, the annual monarch migration through Missouri marks the seasonal change from summer to fall.