Michigan Monarch Prepares for Migration to Mexico

Feeding monarch, October 8, 2022
My camera phone captured a brighter color, but to my naked eyes, the monarch wings were very dark brown.

On a cold, windy morning in early October while walking in Petoskey, Michigan, I spotted a monarch butterfly tucked inside a pink garden cosmos, also known as a Mexican aster. As I neared the flower, the monarch ignored me, letting me sidle up while snapping photos with my camera phone. I had never seen a butterfly behave this way. Normally, they flit away before I get within a few feet.

I wondered about the motionless monarch. Was it dead but held in place by its feet? The bottom segments of a butterfly’s legs are called tarsi, plural for tarsus, and they are used to grip leaves and flowers and to taste potential food. If the butterfly was dead, would rigor mortis cause the tarsi to adhere to the flower? And was the nearly dark-brown color on the ventral side of its wings also a sign of death? (Nature show idea: Insect CSI—because there is a CSI for everything.) After some research, I learned that at the end of its life, a butterfly’s colors fade and its wings often look tattered. This butterfly was neither pale nor shabby. Perhaps the overcast sky made the tightly closed wings appear darker.

My next theory involved the weather. Was the monarch using the flower as shelter from the sharp winds and biting cold? It was 38 degrees with 20-mph winds. If I hadn’t been wearing my stocking cap, mittens, and winter coat, I might have nudged the butterfly and crawled inside the flower next to it. However, if the butterfly wanted shelter, the nearby bushes, trees, and tall grasses would have provided better sanctuaries. Monarchs like to hide under drooping foliage, in hollow trees, at the bottom of tall grasses, or underneath rocky outcroppings.

Finally, I wondered if the monarch was guzzling nectar for its upcoming flight to Mexico. Back home the squirrels in my yard were stashing food, digging tiny holes in the lawn to bury tasty tidbits and pilfering sunflower seeds from my birdfeeders, competing with chickadees, nuthatches, goldfinches, and cardinals—all bulking up for winter. I sympathized. The onset of cold weather changes my appetite. I want to ditch salads and veggies and eat hot soups accompanied by slices of a crusty flax-and-sunflower-seed bread made at a local bakery.

While I took pictures, the garden cosmos waved in the wind, but the monarch, whether dead or alive, remained motionless. Once more, I thought it was dead and stuck to the florets at the center of the flower. I didn’t touch the monarch because if it was alive, I didn’t want to disturb it or harm it. Touching a butterfly’s wings damages them. The colored “dust” that appears on your fingers is actually scales from the wings. Touching the wings might not kill the butterfly immediately, but the scales dislodged by human fingers won’t grow back, and that shortens a butterfly’s life. I continued my morning walk and juggled my theories. On my return, the motionless butterfly still clung to the pink cosmos that whirled in the unfriendly wind under a cantankerous sky.

Pink Garden Cosmos, also known as a Mexican Aster

On my afternoon walk, I stopped by the flower again, but it was empty. I scanned the ground, but found no corpse. I decided to research monarch migration.

There are four generations of monarchs every year. In the fall, generation-four monarchs need to consume loads of nectar—bacchanalian style—because they must build up a layer of fat, as most of them migrate to Mexico. When a butterfly finds a suitable flower, it uncoils its long hollow tongue, inserts it in the flower, and siphons up the nectar. The swilling monarch, whose picture I took on October 8, was most likely a generation-four monarch.

Biologically different than its previous three generations, generation-four monarchs will live eight to nine months. Hatched in September and October, they migrate to Mexico shortly after emerging from their chrysalises. Monarchs west of the Rockies migrate to coastal California. A limited number of generation-three monarchs will also migrate, but generations one and two have a lifespan of only two to five weeks and never migrate south.

In the late winter, generation-four monarchs return to the United States but only into the southern regions where they lay eggs then die. Those eggs become generation-one monarchs that fly into the southern Midwest region and lay eggs that become generation-two monarchs, which fly into the northern United States and southern Canada, laying eggs that become generation-three monarchs. Then generation three lays the eggs of generation-four monarchs that will migrate to Mexico. What a glorious cycle!

My curiosity about a sluggish monarch slurping nectar in a pink cosmos led me to discover that my knowledge about monarch migration had been incomplete.

My big discovery? Not all monarchs migrate to Mexico, and those that do only return partway in the spring.

And the monarch butterfly I saw in October? It was probably hungry, bulking up for its migration to Mexico. It was a cold morning, 38 degrees, and it needs to be 55 degrees before monarchs will fly. Also, monarchs move slowly when it’s cold because the chemical reactions in their muscles slow down, which explains why the monarch I saw let me get so close.

Later that afternoon the temperatures were in the low 50s, maybe higher in the bright sunlight in my mother’s neighborhood. I don’t know if the weather warmed up enough for the monarch to fly away, but because it was gone and I didn’t find it on the ground, I assumed it took flight. A bird could have tried to eat it, but birds usually release a monarch once they taste its poisonous chemicals, and they learn to avoid monarchs. Fortunately, a monarch usually survives a bird’s bite. If you see a monarch with a section of its wing missing, chances are it was bitten then released by a bird. A monarch’s large wings help ensure it will be able to fly even with a missing piece.

Hopefully, the monarch I saw made a successful trip to Mexico and is clustered in trees with millions of other monarchs, keeping each other warm, enjoying a rest before the northward migration begins in the spring.

The people who live across from this field planted these flowers.
I like to believe they did it for the butterflies.

[How to tell a monarch from its doppelgänger, a viceroy: Viceroy Butterfly vs. Monarch]

[For more information: Monarch Joint Venture, Monarch Watch: Biology, Butterfly Basics, Monarch Butterflies Start Long Journey South for Winter, Monarch Butterfly Migration (Escanaba, Michigan), Journey North: Monarch Butterflies, Monarch Watch, Biology, U.S. Forest Service: Migration and Overwintering, Winter Survival Strategies of Common Wisconsin Butterflies]

7 thoughts on “Michigan Monarch Prepares for Migration to Mexico

  1. I love learning new things. This was fascinating. Thank you. I never knew anything about the generations of butterflies and how only the third generation comes this far north. Locally, people are trying to leave “ditch flowers“ for the various pollinators and spreading milkweed for the monarchs. Progress! Funny that it’s progress toward the way things used to be.

    Sent from my iPhone

    >

    Liked by 1 person

  2. Funny how a sighting like that can lead to a lot of learning! As a child, I used to raise monarchs. We had a field across from our house that had loads of milkweed. So satisfying to see the beginning of their life cycle.

    Liked by 1 person

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