Butterflies Eat Their Peas

Silver-spotted Skippers are wide-ranging butterflies that are active from May through early fall. When their wings are folded or when they’re in flight, a large silvery patch on their otherwise mostly brown wings makes them easy to identify.  The butterfly is named for this marking.

Silver-spotted Skipper

Silver-spotted Skippers open the upper (dorsal) side of their wings to the sun when they are basking, revealing markings that resemble a stained-glass window.

Silver-spotted Skipper, basking in the sun.

I have to wonder if the silvery wing spot is an adaptation to make this butterfly resemble bird droppings. Insects, even butterflies, can be an important source of food for birds and some predatory insects.  This disguise would likely give Silver-spotted Skippers some protection from these predators, since bird droppings don’t attract them.

Silver-spotted Skipper, eating minerals from bird droppings. Does that silver splotch on the wings seem like a good disguise?

Silver-spotted Skippers can be seen drinking nectar from a variety of blossoms in meadows, along roadsides, marsh edges, and open woodlands, any place where they can also find the food their caterpillars require.

Silver-spotted Skipper drinking nectar from Indian Hemp (Apocynum cannabinum)

Silver-spotted Skipper drinking nectar from Common Milkweed (Asclepias syriaca)

So what’s the connection to peas?  While Silver-spotted Skipper butterflies drink nectar from many different plants, it’s their caterpillars that ‘eat their peas’. Silver-spotted Skipper caterpillars specialize on certain members of the Pea (Fabaceae) family, including Black Locust (Robinia pseudoacacia) trees, and several herbaceous (not woody) plants  called Tick-trefoils (Desmodium species).  The caterpillars typically munch on the foliage, flowers or buds of these plants, but they do it in such a discreet way that you would only notice if you were looking for it.

The Tick-trefoils all have three-parted leaves, and a tall-stemmed flower cluster. The pollinated flowers produce a chain of fruits that break apart when they’re ripe.  Fruits disperse as hitchhikers on passing animals, including humans.  I’ve often warn them home after a walk in the woods. This dispersal habit is the reason for the ‘tick’ part of the common name of these plants, since the fruits cling to an animal’s fur or clothing like a tick might.

Naked-flowered Tick-Trefoil (Desmodium nudiflorum) flowers and fruit

Naked-flowered Tick-Trefoil (Desmodium nudiflorum) flowers and fruit

Naked-flowered Tick-Trefoil (Desmodium nudiflorum) foliage

Naked-flowered Tick-Trefoil (Desmodium nudiflorum) foliage

Some of the food plants on which the Silver-spotted Skipper caterpillars depend are especially garden-worthy. Blue False Indigo (Baptisia australis), also called Blue Wild Indigo, and other plants of this genus are potential food plants for Silver-spotted Skipper caterpillars.  Its vivid purplish-blue flowers are primarily pollinated by Bumble Bees, but they are visited by other insects as well.  Blue False Indigo can grow to a maximum height of about 4 to 5 feet (1.25 to 1.5 meters), likes full sun to part shade, and can tolerate dry and clay soils.

Blue False Indigo (Baptisia australis) with likely pollinator

Blue False Indigo (Baptisia australis) with Silver-spotted Skipper

American Wisteria (Wisteria frutescens) is another favorite of Silver-spotted Skippers.  It is a deciduous vine with long hanging clusters of violet flowers in early summer, great for use on an arbor or fence.  If its flowers are pollinated, they are replaced by long pea pods later in the season.

American Wisteria (Wisteria frutescens)

American Wisteria (Wisteria frutescens) fruit

Female Silver-spotted Skippers lay eggs on the leaves of their caterpillar food plants. The caterpillars hatch from the eggs, spinning silk to pull the leaves of their host plants together to create a shelter.

Silver-spotted Skipper caterpillar in a shelter it created using its own silk and American Wisteria (Wisteria frutescens) leaves

Silver-spotted Skippers are not alone in their dependence on Pea family members. Gray Hairstreaks and Eastern-tailed Blues are among the other butterflies whose caterpillars ‘eat their peas’, using some of these same plants.

Female Gray Hairstreak butterfly preparing to lay an egg on flower buds of a Tick-trefoil

Eastern-Tailed Blue butterflies mating

Resources

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. 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

Spira, Timothy A. Wildflowers & Plant Communities of the Southern Appalachian Mountains & Piedmont.  2011.

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

Illinois Wildflowers

Missouri Botanical Garden

 

 

 

 

A Butterfly Garden that Embraces the Shade – Spring

Spring Azure nectaring on Virginia Sweetspire

Spring Azure nectaring on Virginia Sweetspire

Our townhouse has a southern exposure, with deciduous trees and the garden on the south, east and west sides, and a common wall with another home to the north. From November through early April, with the leaves off the trees we get a lot of sun, helping to keep the house warm and the heating bills low. As the leaves unfold, the house and garden is well shaded, minimizing the need for air conditioning. “Passive solar”, courtesy of nature, free for the taking. We love the trees.

In nature, different species need to spend parts of their lives at different levels of the forest, some at or below ground level, some just above it, some a few feet higher in shrubs, and others in the trees, even all the way to the tree canopy. So the strategy for our garden is to have a broad diversity of plants mimicking a small slice of deciduous woodland, with a mix of trees, shrubs, and herbaceous plants including perennials, ferns and sedges.

Having a good mix like this accommodates a wide variety of interesting residents, including butterflies, birds, bees, moths, spiders, wasps, flower flies, ants, tree crickets, katydids, and others I’m still trying to identify. A good mix of critters means that they’ll all help keep each other in balance, with no one species dominating, and no need for chemical intervention.

Bad-wing Moth with white form of Common Blue Violet

Bad-wing Moth with white form of Common Blue Violet

During the winter months we enjoy the silhouettes of the trees, shrubs and spent perennials, and the birds that visit them. In March the transition to spring begins, with buds swelling and leaves beginning to emerge from the soil. By April the first flowers appear, at multiple layers in the garden.

Before the trees unfold their leaves, among the first blossoms to appear are those of Red Maple, Northern Spicebush, and Golden Ragwort. Although Mourning Cloaks generally prefer sap, I have actually seen them nectaring on Red Maple flowers. Spring Azures are pretty eclectic in their beverage tastes, even sipping from the starburst yellow flowers of Spicebush.

Heartleaf Foamflower, Green and Gold, Creeping Phlox and Canadian Wildginger quickly join the mix, while Virginia Creeper leaves begin to unfurl, adding to the ground cover.

Spring Garden - Foamflower, Golden Ragwort, Virginia Creeper, Christmas Fern

Spring Garden – Foamflower, Golden Ragwort, Virginia Creeper, Christmas Fern

As the days warm in April, violets begin to bloom. We have three well-established species: a white form of Common Blue Violet, the purple Schrank Alpine Violet, and Striped Cream Violet. They are spreading with the aid of ants, who eat the tasty eliasome attached to violet seeds and then discard the seeds, effectively planting them. Last year a friend gave us a species with interesting lobed leaves, Early Blue Violet. All are available for fritillaries to lay their eggs nearby in late summer so their caterpillars, after spending the winter in leaf litter, can feed on them as both begin to grow in spring.

By late April or early May, Golden Zizia, Spotted Geranium, and Greek Valerian are all in bloom. Black Swallowtails may use Golden Zizia as caterpillar food plants, although they are also very willing to use the parsley and dill we grow in pots on the kitchen patio.

Spring Azure nectaring on Spotted (or Wild)Geranium

Spring Azure nectaring on Spotted (or Wild)Geranium

May brings blossoms at all levels of our woodland garden. Tuliptrees flower as high as their canopy, attracting bees with their copious nectar. Flowering Dogwood’s white bracts and Blackhaw Viburnum’s large round clusters of tiny white flowers light up the understory.

Flowering Dogwood

Flowering Dogwood

The shrub layer is graced with Gray Dogwood, Mountain Laurel, and Virginia Sweetspire. Many Azure butterflies favor dogwood and viburnum flower buds as caterpillar food sources, and will lay their eggs there. Ants protect Azure caterpillars from predators in exchange for the sweet honeydew they excrete.

Silver-spotted Skipper nectaring on Mountain Laurel

Silver-spotted Skipper nectaring on Mountain Laurel

Leaves of White Baneberry (a.k.a. Doll’s Eyes) and Common Ladyfern, Marginal Woodfern, Christmas and Northern Maidenhair Ferns are now available for perching or basking platforms. The male Zabulon Skipper pictured here is working to attract a mate.

Zabulon Skipper posing for a prospective mate

Zabulon Skipper posing for a prospective mate

While I watched him, when another butterfly flew by, regardless of species – Red Admirals, anglewings or swallowtails – he chased them away. With mission accomplished, he returned to a horizontal perching platform provided by White Baneberry leaves or the tips of a Christmas Fern frond, both along the edge of the moss path that curves through the garden. They offer the perfect elevation and exposure for the skipper to show himself off to prospective mates.

The secret is to choose plants that are naturally adapted to a woodland environment. They’ll be happy with the soil, moisture, and available light with minimal intervention from you, and no chemical fertilizers. Most of these perennials bloom for about 6-8 weeks, although Green and Gold may bloom throughout the summer if you deadhead. The shrubs usually flower for 2-3 weeks. After a warm winter, blooming may begin weeks earlier than usual. This past January I saw Golden Alexander in bud – a little scary!

So there is plenty of interest in the garden in spring. But what will bloom in the shade of summer and fall? And what butterflies will visit? Stay tuned!

See below for a list of scientific names for the plants featured in this post:

Red Maple (Acer rubrum)
Northern Spicebush (Lindera benzoin)
Golden Ragwort (Packera aurea)
Heartleaf Foamflower (Tiarella cordifolia)
Creeping Phlox (Phlox stolonifera)
Green and Gold (Chrysogonum virginianum)
Canadian Wildginger, Wild Ginger (Asarum canadense)
Common Blue Violet (Viola sororia)
Schrank Alpine Violet, Labrador Violet, American Dog Violet (Viola labradorica)
Striped Cream Violet (Viola striata)
Early Blue Violet (Viola palmata)
Golden Zizia (Zizia aurea)
Spotted Geranium (Geranium maculatum)
Greek Valerian (Polemonium reptans)
Tuliptree (Liriodendron tulipifera)
Flowering Dogwood (Cornus florida)
Blackhaw (Viburnum prunifolium)
Gray Dogwood (Cornus racemosa)
Mountain Laurel (Kalmia latifolia)
Virginia Sweetspire (Itea virginica)
White Baneberry, Doll’s Eyes (Actaea pachypoda)
Common Ladyfern (Athyrium filix-femina)
Christmas Fern (Polystichum acrostichoides)
Marginal Woodfern (Dryopteris marginalis)
Northern Maidenhair Fern (Adiantum pedatum)

Note:  This is part 2 of a 3 part series.  To see part 1, click here: A Butterfly Garden that Embraces the Shade.  For Part 3, click here:  Embracing the Shade:  Summer and Fall

This article was also published in the Spring 2013 issue of Butterfly Gardener, a publication of the North American Butterfly Association.