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The Flight of a Massachusetts Super Monarch

Monarch butterfly with purple flowers

A New Beginning

It's a late August afternoon in Western Massachusetts. A female Monarch butterfly settles onto a milkweed leaf to deposit eggs, some of the many hundreds she has already dispersed within area gardens. The eggs are very small, white, and sticky enough to remain attached to the underside of leaves. It's important that the eggs be secured to milkweed, as it is the sole food for Monarch caterpillars.

After her task is complete, she flies off. At five weeks old, the Monarch is nearing the end of her adult life as a summer butterfly whose main goal is to mate, reproduce, and create a new generation of Monarchs that will migrate nearly 3,000 miles from Western Massachusetts to their warmer winter home in Mexico.

After several warm August days, one of the whitish eggs begins to turn black and crack open. Out pops a black caterpillar head with a somewhat translucent body. Dana, the newborn baby Monarch caterpillar, otherwise known as an insect larva, has arrived into the world.

Monarch Caterpillar Emerging from Her Egg

 

Her first job is to eat the remains of her egg shell, which is rich with nutrients, giving her a jump start before she begins munching on her only food source: milkweed leaves. Luckily, in North America, there are over a hundred varieties of the plant. Dana lives in a public pollinator garden that has plentiful fresh milkweed with no harsh pesticides to harm her.

Growing and Growing

After a couple days full of munching on leaves, Dana has grown to the point that her skin is feeling tight around her. She finds a safe place on the underside of a leaf and clings to it. Her skin begins to split open starting at her head, revealing a new, softer skin beneath. Dana spends the next couple hours wriggling out of her old skin, shedding it behind her in a process known as molting. As soon as she has fully cast off her original skin, her new soft skin begins to harden around her, which is important since caterpillars are insects who have no bones and instead rely on their outer skin or skeleton to provide their bodies with structure.

Monarch Caterpillar Eating Milkweed

 

Over the next week, Dana continues to eat milkweed leaves, with occasional breaks and nighttime rest. Every few days, she grows enough that she needs to shed her old skin for a roomier new one. She molts four times until she reaches a full length of two inches. Her body mass has increased approximately 2000 times since hatching. See how big she has gotten below!

 

Monarch Caterpillar Instars

 

It has been eleven days since Dana rose out of her egg. She is now a fully grown Monarch caterpillar and she is about to undergo her final and most remarkable change.

A Glorious Transformation

Dana climbs down the stalk of the milkweed plant and crawls along the garden floor to a thick sturdy vine nearby. She finds a winding curved portion, clings to it with the full length of her body, and begins to spin a fine thread of silk from a gland just below her mouth. The silk is woven into a little patch onto the vine. Dana then attaches her back feet to the silk mat and drops her body downward so that she is hanging upside down from the vine.

After she has been hanging a couple hours, her outer skin begins to crack starting at her head, and once again she begins to wriggle the old skin away from her head and toward the vine. This time she is isn't revealing a new skin. As her old skin falls away, what emerges is a bright green outer coating. Dana the caterpillar has now disappeared entirely. Where once her caterpillar body hung, there is now a fully green outer shell known as a chrysalis. Dana is now a pupa in her transition between her immature caterpillar state and her final adult state as a butterfly.

Caterpillar to Chrysalis hanging on a vine

Since the mid-September temperatures, particularly in the evenings, are beginning to drop, Dana is taking longer to grow than her mother, who emerged from her chrysalis after only nine days. Larva and pupa development are affected by temperature, with warm temperatures accelerating growth and cooler temperatures slowing progression.

While in her chrysalis, Dana's body is undergoing a magnificent change. Her sharp mouthparts, which were used to chew through leaves as a caterpillar, are now being replaced by a long tube so she can draw nectar from flowers as a fully developed butterfly. Her caterpillar digestive system, used for breaking down leaves, is now being replaced by a new simpler digestive system for digesting nectar. Days pass and her chrysalis hangs quietly as all these changes occur inside. On the tenth day, Dana's chrysalis begins to turn from green to clear, allowing for the rich black and orange of her newly formed wings to show through. A couple days later, her clear shell turns frosted in appearance, a sign that Dana's body is pulling away from the walls of the chrysalis.

A Monarch Butterfly Emerges!

Suddenly the chrysalis shakes and the outer tip begins to crack, revealing Dana's head. She extends her long black legs outward and slowly begins to emerge out into the world. She holds onto her chrysalis for the next couple hours, pumping blood out to her wings, allowing them to unfold, expand, and flatten out. Then suddenly, without any practice, she beats down her wings and rises into the afternoon air to explore her world from above as a Monarch butterfly.

Monarch Butterfly Emerging from Chrysalis

 

Dana no longer looks for milkweed, but the blooms of a variety of flowers out of which she can suck nectar with her long proboscis, or drinking tube. She lands on goldenrod and aster, sucking up nectar. In the evening, she rests by finding shelter within a tree. When the sun begins to emerge the next day, she walks out onto an outer branch to sun herself in the morning rays, waiting until she has warmed her body enough to take flight again. Monarchs cannot fly until their wing muscles reach approximately 55 degrees Fahrenheit. Being unable to fly when they are too cold can put them in danger if they drop down from a tree canopy or plant, exposing themselves to predators on the ground.

Monarch Searching for Nectar

 

Dana, who emerged as a young caterpillar at the start of September, is part of the super generation of Monarchs that delay mating and reproduction and instead use their energy stores to begin the long migration to their winter home in Mexico. Monarchs are the rare butterfly species that cannot survive cold winters and instead travels across the country to warmer climates until spring time arrives. It will take Dana until November to make the journey south, flying approximately 25-30 miles a day depending on the weather conditions. Along the way, she will need to find nectar to nourish herself and shelter to rest during the evening hours.

Once she arrives in Mexico, she will gather alongside her many fellow Monarchs, living off of her energy stores gained during her cross-country trek, but still needing to find water sources to keep herself hydrated. When spring comes in early March, she will begin mating, reproducing, and leaving eggs on milkweed leaves during the start of the migration back to the northeast United States, but this time she won't return. She will have lived her full lifespan of 8-9 months and her children will continue the journey north. Unlike the fall migratory Monarchs, her children will immediately begin to mate and disperse eggs during their travels. Non-migratory Monarchs typically live between 2-6 weeks with only the super generation or migratory generation living 8-9 months. It will take several generations until some of Dana's great grandchildren and most of her great great grandchildren begin the journey back south to Mexico again.

Monarch Butterfly Migration

Dana's Pollinator Garden

Dana's story was inspired by our frequent trips to the Springfield, MA, Museum Complex, which boasts manicured gardens, including a pollinator garden during the spring, summer, and fall seasons. Monarchs can be seen gliding above the blooms in the many freely accessible gardens. Much gratitude to the kind volunteers of the Western Massachusetts Master Gardener Association who maintain the gardens for the endless enjoyment and exploration of all!

References:

Monarch Joint Venture, Annual Life Cycle, Accessed 9/24/21 from https://monarchjointventure.org/monarch-biology/annual-life-cycle.

Oberhauser, Karen S., and Michelle J. Solensky, editors, (2004) The Monarch Butterfly: Biology and Conservation, Cornell University Press, Ithaca, New York, pages 3-7, and 79-83.

Pringle, Laurence. (1997) An Extraordinary Life: The Story of a Monarch Butterfly, Orchard Books, New York, New York.

United States Department of Agriculture, Monarch Butterfly Migration and Overwintering, Accessed 9/24/21 from: https://www.fs.fed.us/wildflowers/pollinators/Monarch_Butterfly/migration/index.shtml.

United States Department of Agriculture, Monarch Butterfly FAQs, Accessed 9/24/21 from: https://www.fs.fed.us/wildflowers/pollinators/Monarch_Butterfly/faqs.shtml.

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