Heronswood Biodiversity Audit

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There are certainly larger butterflies to observe in early to mid-spring, and the most common among them are from the Brushfoot family (Nymphalidae), notably the Tortoiseshells (Aglais and Nymphalis genera), and Angelwings and Commas (Polygonia genus). These genera enter diapause differently than the gossamer wings, able to withstand the cold as adults in natural crevasses or in abandoned, man-made structures.

On the ventral side of this family’s wings, many scales are colored in broken patterns and splotches of grays and browns. This coloration supports their suspended state as it camouflages them from predators to render their profile as a dead leaf. Mourning Cloak (Nymphalis antiopa), a cosmopolitan species the world over, frequents woodlands and neighboring forest openings along riparian corridors, and can be found consuming a variety of deciduous tree and shrub species as a caterpillar. Adults on the other hand prefer the sweetness of tree sap or even fermenting rotten fruit. Milbert’s Tortoiseshell (Aglais milberti) and Satyr Angelwing (Polygonia satyrus) enjoy a similar diet paired with flowers; however as caterpillars these species rely exclusively on nettles (Urtica sp.).

Another early butterfly from this family, the Green Comma (Polygonia faunus), is an all-around generalist feeder. Adults will nectar from flowers, puddle at mud, and visit herbivorous animal scat for nourishment. As a caterpillar, this species feeds on native willows, birches, and azaleas.

To round out a final group of butterflies present early this season are members from the Sulphurs, Marbles, and Whites family (Pieridae): Sara’s Orangetip (Anthocharis sara) and Margined White (Pieris marginalis). These species enter diapause as pupae, later flying by early to mid-March to seek out toothwort/bittercress (Cardamine sp.) and rockcress (Arabis sp.) as both a larval host plant and to drink nectar.

The aforementioned species are not the only species present during spring, so keep an eye out as an astute observer for a few others not listed here, and be sure to have a camera or field guide handy.
Witnessing the gentle swell of butterfly activity as flowers and leaves emerge with warmth and sun to coax them from their slumber is encouraging with every new season of gardening.

Despite this, butterflies aren’t without their struggles. Reports in recent years of invertebrate population declines worldwide are affecting all manner of butterflies, too. Resources that serve as identification aides often list host and nectar plants. For the intrepid gardener that wishes to see more of their local species, these are a great place to start; but the support need not stop there! Simply making small maintenance changes to garden cleanup, like waiting to prune and cut back grass and perennials until new growth is emerging, can make a difference. Leave some spots to grow wild as native forest or border, and try to leave a layer of fallen leaf debris at the end of a season for overwintering stages. Providing sunny rocks to bask upon or moist, sandy spots to puddle at will also benefit all butterflies.

So long as food and shelter are provided for these delights of the animal world, their existence can be assured for future generations to inspire both curiosity and wonder.

Matt Jevnikar
Heronswood Horticulturist


Photo credit: butterfly.ucdavis.edu

Aglais milberti

Photo credit: BugGuide

Polygonia satyrus

Photo credit: butterfliesandmoths.org

Polygonia faunus

Photo credit: naba.org

Anthocharis sara

Photo credit: butterfly.ucdavis.edu

Pieris marginalis

Photo credit: butterfliesandmoths.org

Some helpful online resources:
Art Shapiro’s Butterfly Site
North American Butterfly Association
Butterflies and Moths of North America
NEA Free Learning Resources