One sure sign that the end of the summer is near are the holes that appear in milkweed leaves this time of year. Take a peek underneath and you might find a great treasure – a chubby caterpillar boldly dressed in yellow, black, and white stripes.
We are currently playing host to two of these voracious larvae at the Stokes Nature Center, satiating their appetites with fresh milkweed leaves in the hopes of witnessing their transformation into a Monarch butterfly.
The incredible story of a Utah monarch begins in southern California in spring. After being dormant throughout winter, an adult female will rouse itself, mate, and begin flying. Monarchs are gliders, meaning they don’t flap their wings much when traveling. Instead they rely on thermal air currents to keep them aloft and moving – traveling up to 80 miles per day. The female flies until she finds habitat suitable for reproduction. There she will lay up to 400 eggs, exclusively on milkweed plants, which contain a toxin that makes caterpillars and adults inedible, or at least unpalatable, to predators.
Eggs of the second generation hatch in April or May. Larvae eat, undergo metamorphosis and keep traveling until they find an ideal place to mate and lay eggs. The adults then die within a few weeks. The third generation hatches in June and July, traveling still farther north and east. This group’s offspring, the fourth generation of the year, are the caterpillars and butterflies we are currently seeing. And this fourth generation does things a little differently.
Once in their adult stage, eating is priority number one. As temperatures turn cool, migration is triggered and the butterflies head for southern California, back to the same place from which their great-grandparents set out in spring. These butterflies live significantly longer than their parents and grandparents, for successful individuals will survive the winter, and start the entire four-generation process over again next year.
Much of a monarch’s migration remains a mystery, and not just how they know when and where to go, but also what routes they use, what habitats they need along the way, and how humans are affecting their movements.
A number of citizen science projects have been established to try and answer these questions. The Monarch Program monitors migration in the western U.S. each fall. Adults are fitted with a small, sticky tag on their right forewing with a color code specific to the tagging site. As these butterflies are spotted again either during migration or at their final destination, data is collected that can help us better understand their journey.
Recent declines in monarch populations make this research all the more important. You can help by cultivating milkweed in your garden to provide habitat to resident monarchs. Anyone with information on the location of caterpillars or chrysalises can contact local Monarch Program volunteer Ron Hellstern for tagging. For more information on tagging and how you can help monarch butterflies, visit our website at www.wildaboututah.org.
For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.
Images: Courtesy &
Copyright 2009 Andrea Liberatore
Courtesy NASA JPL, climate.nasa.gov
Courtesy US Fish and Wildlife Service,
Text: Andrea Liberatore,
Stokes Nature Center in Logan Canyon.
For Information On Tagging:
The Monarch Program: http://www.monarchprogram.org
To tag butterflies found in Cache Valley, please contact Monarch Program volunteer Ron Hellstern at 435-245-9186. Please note that captive caterpillars or chrysalises are easiest to tag, as capturing adults can harm their wings.
Monarch Watch, Propagation (Growing Milkweeds). http://www.monarchwatch.org/milkweed/prop.htm
Pyle, Robert Michael. 1981. National Audubon Society: Field Guide to Butterflies, North America. Alfred A. Knopf: New York.
Monarch Watch: Monarch Life Cycle. http://monarchwatch.org/biology/cycle1.htm
National Geographic: Monarch Butterfly (Danaus plexippus). http://animals.nationalgeographic.com/animals/bugs/monarch-butterfly/