Those flitting clouds of mottled orange and brown painted ladies that swept down the Front Range late last month were just a pale pretender to the main insect migratory event for October: the monarch butterfly’s annual flight to central Mexico. – Dana Coffield
Now’s the time: Chilly night temperatures may have put the monarch migration on fast forward, but keep your eyes open for waves of fluttering insects with bright orange and black windowpane wings heading for warmer wintering grounds. Monarch caterpillars get the cue to begin their metamorphosis into butterflies from cooling temperatures and shorter days. “Monarchs migrate down from all over the U.S., along the east side of the Rockies,” explains John Watts, curator of the Butterfly Pavilion in Westminster. “They take the same routes the birds tend to take, so they have those tail winds to help them.”
Ready to move: Monarchs can make the long flight because their 9-month lifespan is three-times the length of other species. Though their wingspan is only about 4 inches, they’re excellent fliers, flapping their wings up to 12 times per second, achieving speeds of 25 miles per hour and sometimes flying as high as 7,000 feet.
Before the show: As caterpillars, monarchs store fat that holds them through the winter and reproduction. They gather fuel for day-to-day flying from nectar-heavy flowers, like butterfly bush, rabbit brush, asters and cosmos. Depending on local food sources, the monarchs may hang around in Colorado through the third week of October.
Down south: In Mexico, they hibernate; then in spring, mate and lay eggs as they are heading north again. Their progeny pick up the northern trail. “It’s their progeny that continue the journey,” Watts says. It may take a few generations to complete the cycle again.
“It takes them about a month to get all the way to central Mexico,” he says. “It’s pretty impressive.”
