Monarchs reign!

Nature bummin’ with Kirk Gentalen

Let’s cut right to the chase—it’s been an epic summer for Monarch butterflies (Danaus plexippus). There’s a buzz in the air (not literally) and just about everyone you ask gets a little giddy (literally) telling stories of recent Monarch encounters. We’ve been hearing comments like “incredible banner year” and “what a resurgence” from Lubec to upstate New York­—and the spectacle undoubtedly extends further west! The excitement feels even more special since just a handful of years ago Monarch sightings were few and far between. A rebound has never felt so good, and that’s including my very historic basketball days.

Monarchs are a marvel on many levels, of course, and their natural history basics can be mind-blowing (not literally I hope). As adults, Monarchs have a 4-inch wingspan, with males slightly larger than females, and their average weight is about half a gram (or a fifth of a penny’s weight). Largish for a butterfly, but relatively small when compared to most long-distance migrants in the animal kingdom. The Monarchs of eastern North America (our Monarchs!) originate from overwintering high in the Mariposa Monarca Biological Reserve in the Sierra Madre Mountains of Mexico, roughly 3,000 miles away. Studies have shown Monarchs at average speeds of about 5.5 miles per hour, weather and wind conditions taken into consideration, of course. I’m no math major, but that’s about 545.5 hours of travel one way, or 3.25 weeks of travel if they flew non-stop, 24 hours a day.

While many butterfly species migrate north each year never to return south (Painted Ladies are a fine example), Monarchs are the only butterfly species known to migrate in both north and south directions. The twist with Monarch migration is that the northward migration is made over the course of several generations. In other words, the butterflies that reach St. George are actually somewhere in the great to great-great-great grandkid range of the “original” migrants that left Mexico sometime in March. Through all that travelling there is no helicopter parenting, no one to tell them where to go, what to do, or when to move. It’s 100 percent instinct with each generation, which is an alternative lifestyle in its own right. Monarchs leaving our St. George, however, make the entire 2,979 mile trip south as adults, taking as much as 2 months to get back to the land where their great-great grandparents overwintered just a year prior. Google maps say for humans it’s a 47- hour drive, custom issues withstanding.

All butterflies go through a four-stage, “complete” metamorphosis. Local Monarch encounters have been focused mostly on three of those stages—caterpillar (larvae), chrysalis (pupae), and adults (eggs are somewhat hard to find)—with representatives of all three stages often found in the same area. Monarchs lay their eggs on milkweed plants (several species) and hatch after three to eight days. The yellow, white and black striped Monarch larva then feast on the milkweed plant, creating fat reserves while ingesting toxins from the plant that are “used” later on to make adults “distasteful” to predators. The larvae “grow larger” through five major molts over the course of about nine to fourteen days. The larvae then find a (hopefully) solid substrate to hang upside down from, shed their striped exoskeleton one final time and molt into an opaque, blue-green chrysalis with small gold dots.

A Monarch caterpillar

Early stage chrysalis

Metamorphosis nearly complete

“Chrysalis” is a term used for the hard shelled pupa that butterflies form rather than a “cocoon,” which is largely a silk casing that moths use in their pupa stage. “Pupa” is often referred to as the “inactive” stage of insects between larvae and adult, but there is actually a lot going on in that hard shell. Enzymes are released that digest most of the caterpillar’s tissues, creating a sort of caterpillar soup. What is not digested are organized cells called “imaginal discs.” These discs were formed while the Monarch was still in its egg, and each was created for an adult body part—eyes, legs, wings etc. Within the chrysalis the imaginal discs use the protein rich “soup” to power intense cell division to rapidly grow the adult body parts. After a couple of weeks the chrysalis turns black/clear and soon an adult Monarch emerges–three body parts, six legs (forelegs are vestigial), wings and all. The wings are droopy at first and have to be pumped full of liquid to harden and stiffen before they can take flight. I have yet to find a word that fully captures just how staggering this change from larva to adult is. And from there the Monarchs head south—always active, always on the move!

Daily sightings of Monarchs have made this summer special and one to remember. It’s been a refreshing resurgence that could not have been predicted just a few years ago. There are many ways to help Monarchs, from protecting milkweed patches to creating habitats in our yards that support Monarchs and butterflies in all stages of development. A simple internet search can be enlightening as to ways to help Monarchs. It’s worth the search!

May this be a trend for the future and may Monarchs be part of the St George summer/fall scene for years to come. They are a special part of summer, and what a summer it has been!

PHOTOS: Kirk Gentalen

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One thought on “Monarchs reign!

  1. Ann Getsinger

    What a brilliant explanation of how the “imaginal discs” work in the “caterpillar soup”. I’ve always wondered about that part of the process. Almost literally mind-blowing. Thank you!

    Reply

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