BREATHTAKING - A monarch butterfly rests on a milkweed flower along a local road. A bee feeds on native bee balm in an area conservation plot. The study of native plants--including both milkweed and bee balm--is an important element of studying monarch butterflies. Star Eagle photo by Deb Bently
By DEB BENTLY
Staff Writer
Wendy Caldwell, executive director of Monarch Joint Venture, has been studying monarch butterflies and their interconnectedness with the environment since her college days beginning back in 2007. She is ready, though, and even anxious to learn more.
The organization she leads is based in the Twin Cities, with offices in California and Michigan. Its purpose is to serve as a clearing house for information and recommendations to assist the many people, groups, businesses and agencies which have a stake in monarch butterflies and their annual migration. “We want to help them make their efforts as efficient as possible,” she explains. At the current time, well over a hundred groups from all over the country have partnered with the organization.
It seems everybody is fond of monarchs.
“Pretty much everyone has a connection with them,” observes Caldwell, “whether it was raising a monarch in a classroom as a child or watching as hundreds of monarchs flew overhead during a southward migration.”
Right now, it is easy to see monarchs all across Minnesota. The first ones typically arrive around Mother’s Day and begin laying their eggs on milkweed plants, some of which are only a few inches tall. Those eggs hatch into caterpillars within about three days. For the next 10 to 14 days, the caterpillar eats, growing so quickly that it must shed its skin 5 times. When it’s reached its maximum size, just under 2.5 inches long, it can crawl as far as several meters away from the milkweed plant which has been nourishing it. Here it will climb to a sturdy location and attach itself, then transform to its chrysalis stage and remain for another 9 to 14 days before emerging, as a full-sized butterfly. Immediately upon emerging it forces circulation into its wings to expand them, but it will be several hours before it is capable of flight. Two to three days later, it is fully mature and ready to reproduce.
This means that the number of monarchs we see increases dramatically beginning in mid to late June as successive generations of butterflies reproduce, laying eggs from May through early August. In August, butterflies begin gathering in areas where nectar-producing flowers are plentiful, and then they fly southward in dramatically large groups. They winter in fir forests in Mexico where, because of temperatures in the range of 40 to 50 degrees, they are relatively inactive and feed only occasionally, if at all. When temperatures begin to rise, a northward migration begins. This time though, the butterflies travel more as individuals. Females, having mated as they left Mexico, begin searching out milkweed plants in Texas, where they lay their eggs and then die, having reached an age of up to 9 months. The widely scattered 300 to 500 eggs each female has laid then hatch and mature. About a month later, the next generation continues northward, following warmer temperatures and the emergence of milkweed—the only plant on which monarchs can lay their eggs.
Butterflies which arrive in Minnesota are two to three generations removed from the ones who left it the previous fall.
All the generations of butterflies hatched in the spring and summer live only about three weeks after reaching maturity. Only the monarchs which emerge in August and then migrate southward live so extraordinarily long.
Although many millions of eggs are planted throughout the northward migration, the number of eggs which make it to maturity is tiny—somewhere around 2-3%. Some are simply not viable, others are eaten by insects or predators. Some even have the eggs of other insects planted inside them and end up being eaten from the inside out.
Those who make it to adulthood are eye-catchingly bright and colorful. Although not necessarily the largest butterflies in Minnesota, they are among the largest, with adults growing to be about 4 inches across.
Anyone interested in further details about monarchs and their life cycle can easily find out more online, including at monarchjointventure.org. The organization partners with a group called Journey North, which maintains a “live” migration map that uses information from volunteer observers to track the monarchs’ northward movement. The more one learns, the more one wants to know about these fascinating creatures.
But the story doesn’t stop there: Far from it.
Caldwell explains that, in addition to being beautiful to look at and fascinating to learn about, monarchs are something of a “gateway to understanding broader environmental issues.”
Their sensitivity to temperature and their complete reliance on one type of plant—one which grows across vast areas of the continent—can provide significant information and a richer understanding of the complex factors which affect not only the monarch, but everyone.
One example is research done over the past few years by scientists at the University of Minnesota. After studying monarchs which developed on milkweed plants exposed to roadside run-off, researchers acquired new information about the way plants draw up and retain road salts and heavy metals.
“Having a species which covers such a broad geographic range and which depends so heavily on well-timed resources helps us see the various influences that different factors can have,” says Caldwell. In other words, interest in the monarch is automatically also interest in milkweed plants. Attention to the butterfly’s northward movement leads to closer attention to the rates at which plants emerge, mature, and reach their various stages of development. This information is helpful in studies about the environment and climate change.
This means that, from Caldwell’s perspective, the fascination and delight monarchs provide have led to understanding and involvement on deeper levels. “Some people see collecting eggs and raising individual butterflies to maturity as a way to help save the monarch,” she observes. “But as we recognize the significance of the factors which affect the butterfly’s place in the environment, we see larger scale efforts that people can advance to.”
Perhaps one way to put it is, saving monarchs opens our understanding of what we must do to restore and preserve everyone’s futures, including those of plants, insects, animals and humans.