Another Migrating Butterfly, and the Plants that Sustain It

Common Buckeyes have been, well, really common this year.

Common Buckeye drinking nectar from Short-toothed Mountain Mint (Pycnanthemum muticum)

That isn’t the case every year in the areas I frequent near the Delaware River in central New Jersey and eastern Pennsylvania.  Common Buckeyes are not year-round residents this far north. They migrate south in late fall to spend the winter in warmer territories, often as far south as Florida.  In migration they can sometimes be seen in large numbers, often moving along the coast in the eastern United States, or sometimes following river valleys.  They migrate north in spring and early summer, sometimes reaching as far north as southern Canada.  Their numbers vary from year to year in these northern locations, becoming increasingly rare the further north they go.

On warm sunny days even in late October, I am still seeing Common Buckeyes often drinking nectar, mostly from flowers that are members of the Aster family.  This family of plants, which includes asters, goldenrods, sunflowers, bonesets, beggar-ticks, and more are typically the most abundant plants blooming in late summer through the end of the growing season.

Common Buckeye nectaring on Aromatic Aster (Symphyotrichum oblongifolium)

Common Buckeyes can also be found basking at ground level, catching the low rays from the late season sun.

Common Buckeye basking

Common Buckeyes frequent open fields, roadsides, gardens, and even beaches, especially where nectar plants are available.

Common Buckeye drinking nectar from goldenrod flowers along the sandy beach at Cape May, New Jersey

Common Buckeyes have a fairly broad geographic range, and have evolved to use a variety of plants as food for their caterpillars, including plantains, figworts,

Lanceleaf Figwort (Scrophularia lanceolata), a caterpillar food plant for Common Buckeye butterflies


Purple Gerardia or Purple False Foxglove (Agalinis purpurea), a caterpillar food plant for Common Buckeye butterflies

Monkey Flower,

Allegheny Monkey Flower (Mimulus ringens), a caterpillar food plant for Common Buckeye butterflies

and Wild Petunia.

Fringeleaf Wild Petunia (Ruellia humilis) a caterpillar food plant for Common Buckeye butterflies

The coloration of the Common Buckeye’s outside hind wing early in the season is mostly tan, with prominent eye spots.

Common Buckeye drinking nectar from Short-toothed Mountain Mint (Pycnanthemum muticum). Note the tan color and eyespots of the hind wing.

The wing color can be quite different in late summer and fall, taking on a rosy hue.  This may be an adaptation that helps Common Buckeyes blend in with the changing color of the surrounding foliage.

Common Buckeye in autumn. Note the rosy color of the hind wing.

Keep an eye out for Common Buckeyes on these last warm days of fall!

Common Buckeyes on goldenrod



Brock, Jim P.; Kauffman, Ken.  Kaufman Field Guide to Butterflies of North America.  2003.

Cech, Rick; Tudor, Guy.  Butterflies of the East Coast.  2005.

Glassberg, Jeffrey.  A Swift Guide to Butterflies of North America.  2012.

Glassberg, Jeffrey.  Butterflies through Binoculars A Field Guide to Butterflies in the Boston-New York-Washington Region.  1993.

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Wagner, David L.;  Caterpillars of Eastern North America, 2005.

Canadian Biodiversity Information Facility: Butterflies of Canada

Butterflies and Moths of North America



Asters Yield A Treasure Trove!

Orange Sulphur on New England Aster (Symphyotrichum novae-angliae)

Orange Sulphur on New England Aster (Symphyotrichum novae-angliae)

A few days ago the weather was beautiful, with temperatures in the mid-60s, cloudless blue skies and a bit of a breeze, so we went for a walk at a wildlife management area in West Amwell, New Jersey.  We were looking for birds, fall fruit and foliage, and any other interesting critters that happened to present themselves.

We didn’t expect to see a lot in the way of butterflies because of the cool temperatures, and because it’s so late in the season.  We didn’t see many butterflies, but those we did see were pretty spectacular.  Orange Sulphurs were out and about, which was to be expected, since they are among the species that stay active as late as November in this area.  But the surprises were a Fiery Skipper and an American Snout, both of which are fairly rare in New Jersey, especially in late October.  All were nectaring on various species of asters, or other aster family members, the goldenrods.

American Snout

American Snout

Fiery Skipper on New England Aster (Symphyotrichum novae-angliae)

Fiery Skipper on New England Aster (Symphyotrichum novae-angliae)

Asters family members are the primary source of food for late season pollinators.  They are prolific in their long bloom period, often continuing into November.  Their flowering structure reflects a very clever strategy, and suggests this plant family’s alternate name, ‘composite’.  What looks to us like a single flower is actually a cluster of tiny flowers, potentially of two different types, ray flowers and disk flowers.

Blue Wood Aster (Symphyotrichum cordifolium)

Blue Wood Aster (Symphyotrichum cordifolium)

The photograph above of Blue Wood Aster (Symphyotrichum cordifolium) shows the classic flower heads of the Aster family:  a circle of ray flowers that look like petals, pale blue in this species, surrounding a cluster of tiny tubular disk flowers in the center of the head.  If you look carefully at the disk flowers in this photo, you can see that the outer rows are open and blooming, while those in the center of the cluster are still in bud.  This gradual bloom habit supports a long period of flowering, offering nectar to fall pollinators for many weeks.  The disk flowers of this plant are a pale yellow in bud and when they first open, then turning pink or magenta as they age.  This color change is thought to be a signal to pollinators, directing them to the receptive yellow flowers which are not yet pollinated and that will reward them with nectar, and steering them away from those blossoms that are already satisfactorily pollinated.  (Plants are so clever!)  Notice the pink and magenta disk flowers in some of the flower heads in this photo.

As soon as the temperature gets into the low 50s on these crisp late October mornings, the Bumble Bees begin foraging on billowing clouds of luminous Blue Wood Asters outside my windows, soon joined by other tiny bees and flies.  Large dense clusters of bright pale blue flowers top the heart-leaved covered stalks of this woodland beauty.  The shape of the leaves is reflected in the species name, cordifolium, and also gives this plant another commonly used name, Heart-leaved Aster.  Pair Blue Wood Aster with White Wood Aster (Eurybia divaricata) and Wreath (Bluestem) Goldenrod (Solidago caesia) or Zigzag Goldenrod (Solidago flexicaulis) for a spectacular late season shade garden display.

New England Aster (Symphyotrichum novae-angliae)

New England Aster (Symphyotrichum novae-angliae)

Favorites for a sunny garden or meadow include New England Aster (Symphyotrichum novae-angliae), which is also seen blooming in many spots along roadsides, and Aromatic Aster (Symphyotrichum oblongifolium), whose intense blue flowers are irresistible to insects and humans alike.

Following are more asters and their visitors.  You never know what treasures asters will yield!

Flower or Hover Fly, Helophilus sp, on Aromatic Aster (Symphyotrichum oblongifolium)

Flower or Hover Fly, Helophilus sp, on Aromatic Aster (Symphyotrichum oblongifolium)

Orange Sulphur on Aromatic Aster (Symphyotrichum oblongifolium)

Orange Sulphur on Aromatic Aster (Symphyotrichum oblongifolium)

Orange Sulphur on Awl Aster (Symphyotrichum pilosum)

Orange Sulphur on Awl Aster (Symphyotrichum pilosum)

Hover or Flower Fly, likely Toxomerus geminatus, on Aromatic Aster (Symphyotrichum oblongifolium)

Hover or Flower Fly, likely Toxomerus geminatus, on Aromatic Aster (Symphyotrichum oblongifolium)

Blue Wood Aster (Symphyotrichum cordifolium) with Bumble Bee

Blue Wood Aster (Symphyotrichum cordifolium) with Bumble Bee

Aromatic Aster (Symphyotrichum oblongifolium) with Common Buckeye

Aromatic Aster (Symphyotrichum oblongifolium) with Common Buckeye

Common Checkered Skipper on Aster

Common Checkered Skipper on Aster

Mating Bees on Aromatic Aster (Symphyotrichum oblongifolium)

Mating Bees on Aromatic Aster (Symphyotrichum oblongifolium)