That most regal of butterflies, the monarch, is a common sight this time of year in the southern Appalachians and down through other southeastern states to Texas. They are heading south, to Mexico. Those of us along their migration route may see hundreds gliding silently overhead on any day between mid-September and mid-October.
It is nearly unimaginable that a creature so small, so fragile, should be able to fly to Mexico, but millions do. One monarch was tagged near Toronto, Canada, and was found, some weeks later, at a winter roost in Mexico. How long would it take you, a thousand times larger than a butterfly, to travel that same distance under your own power?
Monarchs accomplish this impressive feat by “fueling up” on the nectar of flowers. Just a little sugary sap sends them on their way. Once they reach their destinations, they may not eat again until the next spring, and rely on a store of fat to sustain them. While the adults eat nectar from a variety of flowers, the caterpillars only eat milkweed. Milkweed grows naturally throughout much of North America, and planting milkweed is a way to increase Monarch numbers. It is best just to plant the milkweed and wait for Monarchs to show up rather than trying to raise them artificially, as this article from the New York Times explains.
Their wintering locations are unique habitats. Monarchs in the eastern part of North America winter in the mountains of Mexico. There the perfect combination of moist and cool, but not freezing conditions, allows the monarchs to slow their metabolism and survive without eating. They neither dry-out nor freeze. They usually huddle together in huge groups of hundreds of butterflies, and I’ve even seen them cluster together high in the tulip trees of the Southern Appalachian mountains on a cool migration evening.
Monarch numbers in their overwintering grounds have declined dramatically since 1990. The all-time low was in 2013, with both 2012 and 2014 also alarmingly low. The good news is that numbers started to inch back up in 2015 and 2016, but there is real concern that this year, after a slew of hurricanes, the numbers might drop again.
If you get a chance to look closely at a monarch, you can tell whether it is male or female. The sexes are patterned differently from each other, but the differences are subtle. The black veins on the hind wings of male butterflies are thinner than the veins of females. The male also has a black spot in the center of each hind-wing.
One of the best places to observe monarch migration is the Cherry Cove overlook on the Blue Ridge Parkway near mile marker 416.
To stand in the midst of a monarch migration, as they suddenly appear over the trees to the north, glide by within a few feet, then drop off the ridge to the treetops in the south, is an immersion into the natural world.
It’s worth the effort.
Male monarch butterfly. Note spots on thin veins of hindwing. Image may not be used without permission.