Wasatch Environmental Update for July 30, 2017
By John Worlock, Member of the Board of Directors
“Iconic Monarch Butterflies”
The word “iconic” is much overused these days, but we think it is an apt descriptor for the Iconic Monarch Butterfly. Most of us have seen some of these beautiful insects, with their large and showy, black, white and bright orange wings. Fewer of us have seen a Monarch caterpillar, but they could also pretend to carry the title of iconic. They’re good-sized bugs, shaped like articulated street-cars, decorated attractively with bands of black, white and yellow.
The caterpillars are rarely seen, not only because they don’t fly around, flaunting their beauty, but also because they are found only on milkweed plants. Milkweed is the only possible food for a Monarch caterpillar, and so their moms wisely lay their eggs only on milkweed plants. That mom does not live long, so it is the butterfly emerging from the caterpillar’s carefully constructed chrysalis who will somehow get the message and continue the family migration northward. Or southward. It takes four generations of butterflies to complete the loop of migration from winter quarters northward and back.
Monarch butterflies, like sage grouse and many other species, are candidates for listing as endangered. While their populations fluctuate wildly from year to year, recent estimates say they are down by nearly 80 percent from the mid-nineties, when systematic counting began. Monarchs need to be numerous to survive as they are susceptible to many threats: for example a single storm in 2002 is said to have wiped out 500 million. This sounds a bit suspect, since it is more than the normal winter population. But, as they migrate northward and reproduce, the migrating populations are much larger than the winter populations.
One important threat to the viability of monarchs is the decline in milkweeds, as marginal farmlands where they used to thrive are threatened both by cultivation and by the herbicides that support monoculture farming. Here in Salt Lake City, we can’t do much about that, but one of our neighbors has planted milkweeds in her backyard and nearby, and now has the pleasure of regular monarch visits and even more exciting, regular emergence and departure of their youngsters.
For us beginners in the admiration, and perhaps the protection, of the Iconic Monarch, she recommends the website: monarchwatch.org.