Monarch Butterflies Under Siege
This year may be one of the worst for the monarch butterfly, experts are reporting. Severe hailstorms in Mexico (one of the monarch’s winter home) followed by fifteen inches of rain has left the population decimated by up to 50 percent this year. Add to that the ongoing issue of habitat destruction, and the future of the monarch begins to look a little shaky.
The monarch population is typically measured by the number of acres of pine trees the butterflies fill in their Mexican wintering habitat. This year, scientists found the smallest area of monarchs overwintering in the 16 years they have been looking–down to 4.7 acres from an average of 18.3 acres.
At the fairy-like weight of a mere .026 oz, these stalwart troopers make the journey from as far as Canada all the way to Mexico–it’s like The Odyssey of the insect world. According to MonarchWatch.org, monarch butterflies cannot survive a long cold winter, unlike most other insects in temperate climates. Instead, they spend the winter in roosting spots–monarchs west of the Rocky Mountains travel to small groves of trees along the California coast, while those east of the Rocky Mountains fly farther south to the forests high in the mountains of Mexico.
No other butterflies migrate like North American monarchs. They travel much farther than all other tropical butterflies, up to three thousand miles. They are the only butterflies to make such a long, round trip migration every year. Amazingly, they fly in masses to the same winter roosts, often to the exact same trees. Part of the problem monarchs are facing is the longevity of the trees within which they roost: Illegal logging in Mexico has destroyed the butterflies’ mountain habitats, while property development in California threatens the eucalyptus trees where they roost there.
In addition to habitat issues and the increasingly severe weather, such as that which the butterflies are facing this year, there has also been a significant increase of planting corn and soybean crops that are genetically engineered to be herbicide-resistant. This allows farmers to use weed killer without hurting the crops, but it also means that little of the monarch’s beloved milkweed is left. No milkweed means no place for the butterflies to breed along the way, a crucial step, obviously, in the survival of the species.