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Monarch butterflies return to North Country

June 29, 2011
By Richard Gast - Franklin County Cornell Cooperative Extension , Adirondack Daily Enterprise

There is a Native American legend that says if you want a wish to come true, you must capture a monarch butterfly, whisper your wish to it and then set it free. The monarch will take your wish to the heavens without making a sound, but the Great Spirit, who hears everything, will know your wish and also see that you have set the monarch free. In appreciation for giving the beautiful monarch its freedom, your wish will always be granted.

The monarch butterfly, Danaus plexippus, which in Greek literally means "sleepy transformation," may be the most recognized butterfly species in the world. They are remarkably beautiful, medium-sized butterflies with black bodies and attractive orange wings that are highlighted with black veins and ringed by bands of black, mottled with white spots. Monarchs are the official state insect of Alabama, Idaho, Illinois, Minnesota, Vermont and West Virginia. And with the exception of the polar regions, monarch butterflies can be found on every continent on Earth.

Using air currents and thermals, North American monarch butterflies migrate between Mexico and the United States and, in some cases, between Mexico and Canada, a phenomenon that sets them apart from all other insects. Even more remarkable is the fact that the migration north is multi-generational, covering distances of up to 3,000 miles and taking several months. Yet each adult butterfly lives only about four to five weeks.

Article Photos

A monarch butterfly hangs from a sunflower.
(Lake Placid News file photo)

The reason for their annual migration northward is a search for milkweed. While adult butterflies extract nectar from flowers, milkweed is the only plant host of monarch larvae.

This is the time of year when monarchs arrive here from the south, anxious to lay their eggs upon the leaves of succulent milkweed plants found growing in meadows and fields, and along roadsides and rights-of-way. Once the eggs hatch, usually in four or five days, it is the only food the larvae will eat.

Monarch caterpillars will grow through four larval instars, each time shedding a skin that they have outgrown. Before shedding their skin for the fifth and final time, they will fasten themselves to twigs and leaves by a sticky thread, and the green pupae that emerge will hang there for 10 to 15 days. During that time, the pupal casings will harden, forming the chrysalises from which the adult monarch butterflies will emerge.

With the coming of cool fall temperatures and shorter days, the last seasonal generation of adult monarchs are born here and across much of the northern U.S. and southern Canada. Unlike the generation of monarchs that made the journey north, the butterflies of this generation, sometimes referred to as the "Methuselah generation," will live for seven or eight months. They will migrate southward at an average pace of almost 50 miles a day, eventually arriving at overwintering sites in stands of oyamel fir growing high in the mountain forests of central Mexico, thousands of miles away. The entire eastern population will have arrived there by late November, so many of them that the combined flapping of their wings will create a clear and constant sound.

There, they will form hibernation colonies and wait for the coming of spring, when - barring disease, predation and winter storms - they will again take flight, this time headed for the Gulf coast states to breed, lay their eggs and die.

The brood hatched in the southern states will migrate northward, breeding along the way. They will arrive at the northern extremes of their range in late spring and early summer, and the cycle will begin once again.

While milkweed is abundant in much of the United States and Canada, as the name indicates, it is considered by most to be a weed. Therefore, it is often eliminated with sprayed chemical herbicides or eradicated inadvertently as fields and meadows are replaced with the sprawl of housing developments, parking lots, shopping malls and industrial centers. Because their survival is dependent upon the preservation of milkweed, monarch survival is threatened by this systematic eradication.

In Mexico, it's logging that threatens monarch survival. Little more than 1 percent of the 2,000 square miles of forest refuge that existed 35 years ago remains. And by some estimates, if the harvesting continues at present levels, the entire forest will be gone by the year 2050. Preserving what forest ecosystem remains is critical if monarch butterflies are going to survive.



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