Creating Habitat for Lepidoptera – Butterflies, Moths, and Skippers
Perhaps the most welcome visitors to our gardens, butterflies enchant us with their vibrant colors and graceful flight. Butterflies, skippers, and their nocturnal counterparts, moths, are insects in the order Lepidoptera, a name derived from the Greek for scaly wings. Look closely and you will see the tiny overlapping scales comprising Lepidopteran wings. Each scale is one color and creates the intricate patterns distinctive to their wings. Butterflies are usually brightly colored while moths tend to have more muted colors. Skippers are dun-colored butterflies that resemble moths. As well as beauty, Lepidoptera add ecological benefit to our gardens. As both pollinators of plants and food for birds, spiders, and other animals, they are important parts of the food web. Butterfly and moth larvae, known as caterpillars, are the main source of nourishment to baby birds. Chickadees need 6,000 to 9,000 caterpillars to feed one clutch of babies. (Tallamy, 2007) It follows that, to ensure thriving bird populations, we need lots of caterpillars. There are over 100 species of butterflies in Virginia and over 400 species of moths. Yet the loss of habitat from development, urbanization, climate change, disease, and pesticides has caused a decline in both butterfly and moth populations. To counteract these threats, home gardeners are eager to plant butterfly gardens full of nectar-rich flowers that attract and sustain butterflies. When planting to encourage butterflies, it is also important to feed the larvae. This article will explore ways in which the home gardener can create a habitat that will protect and nourish Lepidoptera in all forms of their lives.
Life Cycle of Lepidoptera
Lepidoptera undergo metamorphosis and have four separate stages in their life cycle: egg, larva (caterpillar), pupa (chrysalis), and adult (butterfly). For simplicity, this article will use the term caterpillar for the larval stage and the term butterfly as a generic terms for adult butterflies and moths.
Eggs and Larvae (Caterpillars): After mating, the female butterfly searches for an appropriate plant on which to lay her eggs. This is the host plant that will feed the hatching larva. Adult butterflies are able to sip nectar from many flowers but most caterpillars can only eat certain varieties of plant and it usually must be a native plant. Monarch caterpillars, who only eat milkweed, are the best-known example of this phenomenon. Some caterpillars can eat multiple native plants, but others are so specialized, they can eat only one species. As they grow, caterpillars molt, or shed their skins several times, eating constantly at each stage. They may spend their entire life on one plant, eating voraciously until they grow large enough to pupate.
Monarch Chrysalis Photo by Melissa King
Pupa (Chrysalis) and Adult: When a caterpillar is mature, it finds a safe place to hide, spins silk, and attaches to a firm support such as a fence post, the stem of a plant, or the underside of a leaf. There it sheds its skin and turns into a pupa or chrysalis. The pupal stage of development typically lasts 10 – 14 days, but some species may over-winter as a chrysalis. The adult butterfly emerges and begins feeding on nectar, tree sap or rotting fruit and drinks water from puddles. The butterfly mates and the cycle begins again. The life span of a butterfly is typically about two weeks and several generations can be produced in one season. Some species live only a few days and others may live several months. As winter approaches, cold-blooded butterflies must find a protected place to hibernate. They may spend the winter in any stage (egg, larva, pupa or adult), hiding in the bark of trees, in stems of perennial plants, in old logs, on fences, or in leaf litter.
Host Plants for Lepidoptera
Trees And Woody Plants: Native trees are some of the most important caterpillar host plants. In the mid-Atlantic, oaks support over 500 species of Lepidoptera. Willows, native cherries and birches support over 400 varieties. Poplars, native crabapple, maple, pine and hickory are not far behind, supporting 200 to 300 species. (Tallamy, 2007) There is a good chance you have one or more of these trees in your yard or in a nearby wooded area. If you are adding plants to your yard, consider one of these native trees rather than a non-native for your landscape. Serviceberry (Amelanchier), hornbeam (Carpinus), redbud (Cercis canadensis) and flowering dogwood (Cornusflorida) are smaller trees that support multiple species of Lepidoptera and one or more should fit in most any landscape. Caterpillars will feast on New Jersey Tea, (Ceanothus americanus), highbush blueberry, (Vacciniumcorymbosum), spicebush (Lindera benzoin), chokeberry (Aronia arbutifolia), winterberry (Ilex verticillata), and native viburnums.
Perennials: Native perennials provide nectar for butterflies, and many are also host plants for caterpillars. Wild strawberry (Fragaria virginiana) blooms in spring and supports 60 species of Lepidoptera. Violets (Viola), meadow-rue (Thalictrum), wild columbine (Aquilegia ) and wild geranium (Geranium maculatum) are another set of must-haves for early emerging caterpillars as they support up to 25 species of Lepidoptera. Milkweed (Asclepias), wild indigo (Baptisia), black-eyed susan (Rudbeckia), sunflower (Helianthus), and rose mallow (Hibiscus) provide nourishment in early to midsummer. Joe-Pye Weed (Eutrochium), boneset (Eupatorium) and New York ironweed (Veronia noveboracensis) offer food for late summer caterpillars. Be sure to include asters (Symphyotrichum) and goldenrod (Solidago) in your fall garden as they support over 100 species of Lepidoptera.
Grasses: Every garden benefits from the addition of native grasses. Switchgrass (Panicum), broomsedge (Andropogon virginicus) and Poverty oat grass (Danthonia spicata) support multiple species of caterpillars. Sedges (Carex) are at home in shady areas and are food sources for various moths and butterflies, including skippers. Grasses are also hiding places for overwintering Lepidoptera in any stage of their cycle.
Skipper on aster Photo by Deborah Harriman
Wild Places and Weeds
Have you seen butterflies flitting around areas that are wild rather than cultivated? Roadsides, medians, parks, and other public settings support butterfly and caterpillar populations if they are thick with native plants and pesticides are eliminated. The next time you walk along a wooded path, notice how many butterflies you see. The undergrowth at the edges of forests hosts many caterpillar species. Plants in these wild areas are often considered weeds and are not typically used in the home garden but are rich in food for both adult and larval butterflies. Native thistle, common milkweed, nettle, dogbane, tick-trefoil and wingstem are examples. In your own yard, is there an out-of-the-way corner, perhaps in the back or behind an outbuilding, where these “weeds” can flourish? If you live next to woods, can you let the undergrowth spread unmolested? Be sure to allow only native varieties to settle in and remove any invasive plants that might try to take over. Virginia creeper is a ground cover that is often considered a nuisance in a manicured bed. Think of it instead as a lovely native ground cover that feeds caterpillars and offers hiding places for them and other creatures. If you have turf grass, can you forego the chemicals needed for the manicured look and let violets, clover and plantain take hold?
Winter Cover
Butterflies are cold-blooded and hibernate in the winter. Different species will overwinter in one of the four stages of their life cycle. Adults might hide in peeling tree bark, under leaves, on old logs or on fences. They might find a spot in a shed, barn or other building. Pupae might attach in a protected spot on a structure, branch, or stem. Leave stalks of native perennial plants standing until spring and allow fallen leaves to lie on the garden beds. These provide secure hibernating spots for butterfly eggs and caterpillars.
Pesticides
The gardener who wants to attract wildlife must avoid pesticides. While often touted as safe for birds, fish, pollinators, and pets, “natural” pesticides can be harmful to caterpillars. Bt (Bacillus thuringiensis) is a bacterium found naturally in the soil and is used in pesticides to kill the larvae of beetles, flies, mosquitoes, and moths. Horticultural oils and insecticidal soaps kill the insects they touch, which includes caterpillars. By following good cultural practices that maintain healthy plants and providing a diverse habitat that encourages a variety of insects and wildlife, the home gardener may be able to keep insect damage in check and avoid chemical controls. As much as we want to “grow” caterpillars, some are unwelcome visitors to our gardens. Monitor your plants and learn to identify those that need to be removed and those that are best left unharmed.
Caterpillars in the Vegetable Garden
If you are growing vegetables or herbs, you will likely see caterpillars on some of your crops. The home gardener usually can live with the damage caterpillars inflict and still have a harvest. Here are three Lepidoptera commonly seen in Central Virginia gardens.
The cabbage white butterfly is ubiquitous and its caterpillar, the cabbage worm, attacks plants in the brassica family — broccoli, cabbage, cauliflower, collards, and kale. The cabbage white is an imported species and, while a nuisance, can usually be controlled organically by the home gardener. If picking them off by hand, using row covers, or living with some damage is not an option, consult you local extension office for organic controls.
Hornworms are the caterpillars of the five-spotted hawk moth and can defoliate a tomato plant. They are large and easy to pick off by hand, but this might not be necessary as nature often takes its course. White, rice-like appendages attached to the hornworm are wasp larvae that feed on and decimate the hornworm — problem solved.
Black swallowtail caterpillars feed on vegetables and herbs in the carrot family – carrot, celery, chervil, cilantro, cumin, dill, fennel, lovage, parsley, and parsnip. This native caterpillar has adapted to these non-native plants and can eat them. The home gardener should decide whether to remove these caterpillars or live with them. Planting multiple crops and planting enough to share is often a good option. Queen Anne’s Lace is a favorite of this caterpillar and can be left to grow in your “wild” place.
Caterpillars on NativeTrees
Bagworms are the larvae of a native moth. They feed mostly on conifers, especially arborvitae, junipers, and cedars. Left unchecked, they can defoliate a small tree, and it can die. They chew on the leaves and spin bags resembling small pinecones where they spend the winger. Bags appear in late summer or early fall. Monitor your susceptible trees, pick off the bags before they hatch in the spring, and destroy them.
Eastern Tent Caterpillars appear in the spring; Fall webworms appear in late summer. They are native to the eastern U.S. and live in groups in silken bags on the branches of native trees. They are commonly found on cherry, apple, and crabapples, but will feed on birch, black gum, willow, witch-hazel, maples, and oaks. Their webs and defoliation can be unsightly, but their foraging is seldom lethal to trees. They have numerous natural enemies that help keep them in check. If a heavy and potentially deadly infestation is present, consult your local extension office to determine proper control.
Spongy Moth (formerly called the European gypsy moth) arrived from Europe in the 1860’s and can be found in most East coast states. Its presence in a landscape can be deadly. A devastating pest, spongy moth caterpillars feed on over 300 species of trees and shrubs. The defoliated trees then become susceptible to diseases and other pests and can die. Learn to identify this caterpillar and report spotting the egg, caterpillar, or moth to your local extension office.
Sawfly larvae resemble caterpillars but are not Lepidoptera and do not turn into butterflies. Learn to identify them as they can severely damage dogwoods, roses, and other plants.
Some Lepidoptera Found in Central Virginia and Their Host Plants
American lady: pearly everlasting, pussytoes
Baltimore checkerspot: turtlehead
Banded hairstreak: oaks, hickories, black walnut
Black swallowtail: golden alexander, rue, Queen Anne’s Lace, dill, parsley, fennel
Common buckeye: plantain, vervain, toadflax
Common wood nymph: poverty oat grass, big bluestem, little bluestem
Eastern-tailed blue: clovers, tick-trefoil
Eastern tiger swallowtail: black cherry, tulip tree, ash
Gray hairstreak: clovers, mallows
Fritillaries: violets
Hummingbird clearwing moth: dogbane, snowberry, black cherry
Monarch: milkweeds
Mourning cloak: willows, elms, birch, hackberry
Painted lady: thistles, mallows, legumes, asters
Pandora sphinx moth: native grapes, Virginia creeper
Pearl crescent: asters
Pipevine swallowtail: Dutchman’s pipe, Virginia snakeroot
Red-spotted purple: black cherry, willows, serviceberry, birch, hawthorn
Silvery checkerspot: wingstem, ox-eye sunflower, black-eyed susan
Spicebush swallowtail: spicebush
Spring azure: dogwood, black cherry
Sulphurs: clovers, legumes
Summer azure: dogwoods, viburnums, wingstem
Viceroy: willows
Zebra swallowtail: pawpaw
Summary:
Plant in layers: trees, shrubs, herbaceous perennials, and ground covers.
Rely on native trees, shrubs, grasses, and perennials that will serve as host plants to caterpillars.
Be sure both nectar and host plants are available in all seasons.
Plant ground covers beneath larger plants to offer caterpillars food and to give them a place to hide from predators. Many moth caterpillars hide during the day and come out to feed at night.
Try to have a “wild” area.
Provide shelter for overwintering Lepidoptera by leaving leaves on the ground in the fall and dried grasses and perennial stems in place until spring.
Many caterpillars feed on multiple varieties of plants, but a number can only feed on one species. The scarcity of these plants makes these butterflies more susceptible to loss. If you see the butterflies noted below in your area, try to include some of their host plants to help them persist:
Spicebush caterpillar Courtesy Missouri Botanical Garden Plant Finder
Dutchmans pipe (Aristolochia macrophylla) for pipevine swallowtails
Pawpaw (Asimina triloba) for zebra swallowtails
Turtlehead (Chelone) for Baltimore checkerspots
The Piedmont Environmental Council and the Master Gardeners of Northern Virginia have more information on hosts plants to include in your Central Virginia garden:
