Monarch butterflies are the only insect that migrates to a warmer climate that is 2,500 miles away each year, and they are one of the few insects capable of making transatlantic crossings.
Monarch butterflies are not able to survive the cold winters of most of the United States so they migrate south and west each autumn to escape the cold weather. The monarch migration usually starts around October but can begin earlier if the weather turns cold sooner than that. If the monarch lives east of the Rocky Mountains, it will migrate to Mexico and hibernate in oyamel fir trees. If it lives west of the Rocky Mountains, it will hibernate around Pacific Grove, California in eucalyptus trees.
Monarch butterflies use the exact same trees each and every year when they migrate, which seems odd because they aren’t the same butterflies that were there the prior year. These are the new fourth generation of monarch butterflies, so how do they know which trees are the right ones to hibernate in?
Each adult butterfly lives only about four to five weeks. But one of the many wonders of the Monarchs is the annual creation of a unique "Methuselah generation." As autumn approaches, a very special generation of butterflies is born. Unlike their parents, grandparents, great-grandparents, and great-great-grandparents -- all of whom had ephemeral lives measured only in weeks -- these migratory butterflies survive seven or eight months. In human terms, given our average life span of 75 years, this would be like having children who lived to be 525 years old! This generation performs the incredible feat of flying from Canada and the United States to the center of Mexico -- after which they begin the northward journey again. Once they reach the United States, a kind of relay race begins: their short-lived offspring, with only four or five weeks to live, continue making the trek northward over several generations.
The common name “Monarch” was first published in 1874 by Samuel H. Scudder because “it is one of the largest of our butterflies, and rules a vast domain." It is sometimes called the "milkweed butterfly" because its larvae eat the plant. In fact, milkweed is the only thing the larvae can eat! Most predators have learned that the monarch butterfly makes a poisonous snack. The toxins from the monarch's milkweed diet have given the butterfly this defense. In either the caterpillar or butterfly stage the monarch needs no camouflage because it takes in toxins from the milkweed and is poisonous to predators. Many animals advertise their poisonous nature with bright colors, just like the monarch!
Do Monarchs abound in your area of the county? If so, where do you live?
1 comment:
I happened to catch a tiny bit of a PBS special on butterflies within the past day or so, and so reading your post was interesting to me. Most butterflies live only 14 days, and these butterfly exhibits (we have one in Houston) have to be constantly replenished. It was fascinating, learning how the plants have to be constantly monitored for health due to some species eating their host. Interesting stuff.
When I was a kid, butterflies fascinated me. Don't pay much attention now, tho. We probably have monarch butterflies, but I couldn't swear to it. Nice writeup, Chuck! Fun reading.
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