By Alan Branhagen
Editor’s Note: We’ve created a new Butterfly Checklist, a companion to the Bird Checklist, available with all of our brochures in the Oswald Visitor Center. The Butterfly Checklist follows observations of long-time Arboretum Naturalist Matt Schuth, butterfly gardening expert Alan Branhagen, and all accepted iNaturalist observations reported on-site at the Arboretum. We hope both checklists will come in handy as you explore the Arboretum.
The Arboretum has a variety of habitats within its 1,200 acres. These include flower gardens, tree and shrub collections; wetlands that include marshes and bogs; prairie, and hardwood “Big Woods” forest. To date, 51 butterfly species have been identified at the Arb from the five main families of butterflies found in the Upper Midwest.
We encourage visitors to use our new Butterfly checklist, and help us learn more about the butterflies at the Arb by reporting your butterfly observations to us. There are additional species we feel must be present but not yet confirmed. Take a photograph and upload it to iNaturalist, where it can be identified and documented for us.
Butterflies are key indicators of a healthy environment, susceptible to misuse of pesticides and other land management activities (including burning and garden cleanup) at all stages of their life cycle (a complete metamorphosis from egg to caterpillar to chrysalis or pupa to adult) and through all seasons.
Adult butterflies get sustenance from nectar, minerals and moisture so regularly visit favorite flowers, tree sap, scat, and mud puddles which they imbibe through unrolling their proboscis. Caterpillars feed upon specific host plants to grow and mature (one species, the Harvester, is carnivorous and eats woolly aphids), shedding their skin on average five times before transforming into a chrysalis or pupa from which the adult butterfly emerges.
It’s amazing most of our butterflies are adapted to survive winter (each species in a specific life stage) with a sort of anti-freeze in them. Whether an exposed egg on a stem, caterpillar rolled in a leaf or in leaf litter, pendant chrysalis or swaddled pupa, or adult butterfly hibernating sheltered under bark or in a wood pile; how we maintain the gardens and habitat at the Arboretum matters to butterflies’ survival. Several of our butterflies are colonists or migrants and do not survive our Minnesota winter, but return the following season from milder climates. The beloved Monarch is poster child of a true migrant butterfly.
There has been an extreme decline in butterfly numbers over the last decade in the region and naturalists are trying to figure out what the cause of this is. Butterflies produce hundreds of eggs each season and have the capacity to be resilient if we give them a chance. The rebound of the Monarch population is a good example of how a regional effort at planting more milkweed helped the Monarch recover.
We feel butterflies are a visceral component to the Arboretum experience. Please enjoy these flying flowers along with the gardens and nature of our special site.
For more information, check out the book, Butterfly Gardening, The North American Butterfly Association Guide, by Jane Hurwitz, available in the Gift & Garden Store, or The Gardener’s Butterfly Book, by Alan Branhagen, which you’ll find in the Andersen Horticultural Library.