Monarch butterflies are traveling folk, and they’re willing to go quite far to do it. Unable to withstand winter conditions in most of the United States, monarchs make like a tree and leave when temperatures turn cool in October. If a monarch lives in the eastern United States, she heads to the oyamel fir forests in the Sierra Madre mountains of Mexico, about an hour north of Mexico City. There they hang out in clumps of thousands of their brethren in the fir trees, chillaxing for the winter.
If a monarch lives in the western United States, it will beat its wings toward California come fall, where it will hang out in a smaller but still voluminous crowd of butterflies in the eucalyptus trees of Pacific Grove.
In the ordinary summer breeding season, the life of a monarch is no more than six weeks long, but a butterfly that reaches adulthood in late summer will live much longer. These butterflies are the migrants, and they will fly as much as 4,800 km to reach their wintering grounds. In February or March, the overwintering butterflies will get their collective freak on and mate, like our friends in the photo above, before reversing the journey north. Most of them will die shortly after they reach their summer homes.
As most of us know, the monarch population has been in free-fall in recent years, due perhaps to a combination of habitat loss, milkweed loss, pesticides, and illegal logging. A scant two decades ago, a billion butterflies spent their winters at the Insect-o-palooza hosted in the Sierra Madre mountains, covering a staggering 19 hectares of ground. Last year only 35 million were left in 1.13 hectares — which was better than the previous year, which hit a grim .67 hectares. Human beings started getting their shit together on this issue only last year, but it looks like it’s working. Initial reports from Mexico indicate that our friends may be occupying up to four hectares this year. The goal is six by 2020.
So everyone go plant some milkweed, but make sure it’s milkweed native to your area. (There’s some evidence that nonnative milkweed may harm them.)
To close, here is a fact that will shoot a thrill down the spine of any naturalist with even the slightest mystical leaning: the wintering monarchs roost in the same trees every year, despite the fact that they’ve never been there before. Yes, nature can transmit directions, if not memory, from parent to offspring, somehow. And this inherited instinct survives the process whereby the monarch morphs from a caterpillar to a butterfly, basically digesting itself into a mass of (mostly) disorganized cellular goo, before rearranging itself into an adult butterfly.
This world, I swear.