Here’s a bit of background:
Unlike most migrating species, monarch butterflies employ an improbable strategy that splits their round-trip migration between generations. Their life cycles must be intricately synchronized with those of the milkweed on which they lay their eggs.
Monarchs returning from Mexico reach the Southeast soon after native milkweeds appear in spring, producing the first of up to three generations that breed on new milkweed through summer. When the perennials start dying back in the fall, a final generation of butterflies typically emerges in a sexually immature state. Rather than reproduce when food is scarce and caterpillars might freeze, they fly to Mexico, to wait out the winter.
In the Midwest, which produces half of Mexico’s wintering monarchs, the scores of wild milkweed species among grasslands and farms are fast disappearing.
Nearly 60 percent of native Midwestern milkweeds vanished between 1999 and 2009, the biologists Karen Oberhauser and John Pleasants reported in 2012 in the journal Insect Conservation and Diversity. The loss coincided with increased applications of the weed killer Roundup on expanded plantings of corn and soybeans genetically altered to tolerate the herbicide. Meanwhile, monarch reproduction in the Midwest dropped more than 80 percent, as did populations in Mexico. Source: New York Times
Like many backyard gardeners, I wanted to do something to help, so I bought a packet of Milkweed seeds advertised as Butterfly Flowers. They are the genus Asclepias incarnata. What I didn’t know is that Swamp Milkweed continues to grow past the time the butterflies should be heading south.
According to the article, our good intentions could be backfiring. Here’s an excerpt:
There’s this huge groundswell of people planting tropical milkweed, and we don’t know what it’s doing to the butterflies,” said Francis X. Villablanca, a biology professor at California Polytechnic University. “We’re all in a rush to figure it out.”
Dr. Altizer fears that when monarchs encounter lush foliage in the fall, they may become confused, start breeding and stop migrating.
“It’s sad, because people think planting milkweed will help,” she said. “But when milkweed is available during the winter, it changes the butterfly’s behavior.”
The times article linked to additional reading including ways to create habitat for Monarchs. I also learned at The Exerces Society for Invertebrate Conservation that its important to plant Milkweed native to our area. I found a site called Larner Seeds and ordered a species of Milkweed better suited to San Jose.
The Butterfly Effect
The butterfly effect is a scientific theory put forth by Edward Lorenz. It’s described this way:
In chaos theory, the butterfly effect is the sensitive dependence on initial conditions in which a small change in one state of a deterministic nonlinear system can result in large differences in a later state. The name of the effect, coined by Edward Lorenz, is derived from the metaphorical example of the details of a hurricane (exact time of formation, exact path taken) being influenced by minor perturbations such as the flapping of the wings of a distant butterfly several weeks earlier.
Ray Bradbury’s uses the butterfly effect in his chilling short story, A Sound of Thunder. Wealthy hunters pay a large sum of money to travel back in time to kill a dinosaur. They must stay on the approved path, and shoot the dinosaur, seconds before the animal dies from a falling tree. The hunter steps off the path and irrevocably alters time. When he returns to the present his reality is permanently altered. Devastated, he looks down at his boot and sees a crushed butterfly.
Could we be witnessing our own ‘butterfly effect’? Please share your thoughts in the comments section below.
Additional Resources on the Monarch’s plight include: