Butterflies and Caterpillars in Your Garden

There is no more delightful decoration for a garden than nature’s own–butterflies. On a warm sunny day these visitors provide color and motion that doubles the pleasure of gardening. How fortunate for the gardener that it takes very little effort to make the yard attractive to butterflies!
Butterflies will visit, and possibly stay to lay eggs, wherever there is a variety of plants for food and shelter, some moisture, and an absence of pesticides. While there are typically more species in warm climates than in cooler ones, there are butterflies almost everywhere in the country. Their appearance in your backyard ultimately depends on whether their favorite plants are growing there–certain ones to support their larvae, many others to support adult butterflies.

Larvae (Caterpillar) Host Plants

The typical garden is not likely to incidentally have plants that host the larvae of most butterflies. The caterpillars of each species are usually are pretty picky, favoring the foliage of specific plants or plant groups at this stage of their lives. Larval host plants are often unattractive, weedy and wild, generally unfit for cultivated gardens [see box]. Yet, adult female butterflies choose these particular plants (Monarch moms must have milkweed!) to lay their eggs on. This assures that newly hatched caterpillars have appropriate food immediately at hand.

Typically, young caterpillars begin voracious feeding immediately after hatching, virtually skeletonizing host plant foliage. Watch a parsleyworm, (a swallowtail caterpillar) devour the foliage of Queen Anne’s Lace, carrots, or parsley! Butterfly larvae grow as they eat, shedding their skins 4 to 6 times before achieving maximum size for pupating. Only then do they desist, becoming immobile in a hard chrysalis suspended from a leaf or stem of the larval host plant until emerging as an adult butterfly.

All-time Butterfly Flower Favorites

-Black-eyed Susan
-Butterfly bush
-Butterfly weed
-Joe-Pye weed
-Purple Coneflower

Butterfly Host Plants

Fortunately, adult butterflies have more cosmopolitan palates. The flower nectar they need for energy is available in lots of different flowering plants. They will visit your yard in search of those that are most easily accessed by their long, coiled tongues, or proboscis, which enables them to reach deeply into the center of flowers where the glands that produce the sweet nectar are located. They are particularly attracted to hot-colored, fragrant flowers. They get further nutrition from moisture from puddles and raindrops, rotting carrion and other liquids–even human perspiration if you stand very still–that provide traces of minerals and nutrients not in nectar.

Butterfly Garden Design

The butterfly gardener’s challenge is to provide diversity of plants in communities throughout the property to support both larvae and adults. Variety is the key. Choose lots of kinds of plants–herbs, annuals, and perennials as vines, groundcovers and in beds, plus shrubs and trees. Wildflower meadows featuring native plants are ideal. Food crops add to the diversity too. Assure that blooms are available to visiting butterflies for the entire season. The greater the variety of suitable plants, the greater the potential number and variety of types of butterfly visitors.

It is not necessary to integrate larval and adult plants throughout landscape. Just allow some part of your yard or nearby property to remain weedy and undeveloped to lure female butterflies to lay eggs. Somewhere in the yard, let fresh water accumulate to support communal “mudpuddling”, so butterflies get soil salts and minerals as well as moisture. Overripe fruit that has dropped from trees also provides nutritious moisture. Finally, butterflies like some flat stones for basking, or sunbathing, to gather warmth to power their wings.

Butterflies visit flowering plants that are in full sun and in sites sheltered from wind in beds or containers. Protect garden beds exposed to the wind with a hedge of glossy abelia or butterfly bushes or a wall or pergola covered with honeysuckle or passionflower. Flowering shrubs provide shelter for roosting too. The more fragrant, the better. Plant at various heights, because like birds, certain butterfly species prefer to feed at certain heights. (Some species are even quite territorial and try to chase others from favorite plants).

Finally, unlike the famous monarchs which migrate to Mexico and other points south, most butterfly species overwinter nearby. This means that their eggs, chrysalises, or larvae are likely to be in or near your yard during the non-gardening months. Some will even hibernate as adults. Do not mow weedy sites and dismantle woodpiles which provide them safe shelter in the off-season.

Caterpillars: Distinguishing Friend From Foe

Butterfly larvae tend to be solitary, or sparsely distributed, whereas pest caterpillars such as fall webworm make tents and hatch in the hundreds. The latter are best handled by pruning the tent out of the tree or breaking it open so that the birds can eat the immature larvae.

However, even in sparse numbers butterfly caterpillars can damage ornamentals or food plants. For example, the ubiquitous white cabbage butterfly lays lots of eggs that turn into destructive green worms which devour cabbage and broccoli and their relatives. An insecticide product containing Bt (Bacillus thuringiensis) sprayed onto plant foliage will handle feeding worms that threaten to destroy crop yields. In the case of parsleyworms on parsley, simply moving them to a non-essential plant such as wild carrot will both save the crop and preserve the eventual butterfly.

Favorite Larval Host Plants:

-Bermuda grass
-St. Augustine grass

The Best Butterfly Blooms Are:

-composites, umbels, and panicles, whose clusters of small florets provide many sips plus a place to pause. -brightly colored in lavender, purple, red, orange and yellow. -single-flowered types where the nectar is more accessible. -flat or tubular in varied lengths. -planted in drifts and clusters for efficient grazing. -fragrant.

Flowering Plants Whose Flowers Attract Adult Butterflies:

Common Name Botanical Name
Aster, New England Aster novae-angliae
Beebalm Monarda sp.
Black-eyed Susan Rudbeckia sp.
Blanket flower Gaillardia sp.
Blazing star Liatris sp.
Butterfly bush Buddleia sp.
Butterfly weed Asclepias tuberosa
Candytuft Iberis sempervirens
Cardinal Flower Lobelia Cardinalis
Catmint Nepeta
Coneflower, Purple Echinacea purpurea
Daisy, Ox Leucanthemum sp.
Gas plant Dictamnus Fraxinella
Goldenrod Solidago sp.
Globe thistle Echinops Ritro
Hyssop, Anise Agastache Foeniculum
Joe-pye weed Eupatorium purpureum
Jupiter’s beard Centranthus ruber
Lantana Lantana Camara
Lavender Lavandula sp.
Lupine Lupinus
Milkweed, Swamp Asclepias incarnata
Milkweed, Common Asclepias syriaca
Mountain bluet Centaurea sp.
Pentas Pentas lanceolata
Phlox, Garden Phlox paniculata
Sneezeweed Helenium autumnale
Sage, Scarlet Salvia coccinea
Tickseed Coreopis sp.
Turtlehead Chelone glabra
Verbena Verbena bonariensis
Yarrow Achillea sp.
Zinnia Zinnia sp.

Provided by the National Garden Bureau www.ngb.org.

Integrated Pest Management

Look for bagworms toward the end of the month. Early detection is important; caterpillars are cleverly disguised and can quickly defoliate plants before they are noticed. Bagworms prefer evergreens such as arborvitae, cedar, juniper, and pine. Tap a branch over a sheet of white paper; look for small, green caterpillars with a small cone of plant debris attached to them. As they grow, they enlarge this cone until it is two inches long. Fully grown caterpillars anchor the bag they constructed to a branch before they become adults. Females fill their bags with as many as 200 eggs after they mate. Hand pick the bags before the eggs hatch to prevent damage. Remove the tough silken threads attaching the bags to the plant. If left on, they can girdle the branches as they grow. Spray infested plants with Bacillus thuringiensis as soon as the caterpillars hatch if bags are too numerous to remove.

Don’t overfertilize your plants. This practice encourages aphid populations which feast on the tender, new growth that results from the abundance of nutrients. Heavy, frequent fertilization usually results in nitrate contamination of ground and surface water as well.

Be aware of your plants’ watering needs during periods of drought. Plant roots, particularly those of shrubs and trees, extend one to two feet below the ground. Deep, infrequent watering is the best approach. This can be done by laying a hose at the base of your plants on a slow drip or programming your automatic drip system to run for an extended period of time at infrequent intervals.

Watch for signs of Seiridium canker on your leyland cypress. Increasingly popular in the southeastern states as a fast growing windbreak and privacy screen, this hybrid evergreen can be easily stressed by prolonged drought or extreme cold, making it susceptible to canker. Watch for signs of resin oozing from cracks in the trunk or branches, dark brown to purplish patches on the bark, and yellow-brown foliage above the canker. Keep plants healthy and vigorous. Aside from adequate moisture, leyland cypress need at least 15 feet of space to minimize competition with other plants; existing plantings can be thinned by removing some of the plants. During drought provide deep, infrequent watering and avoid overfertilizing. Prune wilted or discolored branches or tips, cutting back to a healthy part of the branch. Severely infected trees should be removed and destroyed.

Keep an eye out for a new scale that has been attacking spruce and other conifers. Fiorinia japonica, a scale similar to the more commonly known elongate hemlock scale, has been found in increasing numbers in the Eastern U.S. The males are white and the females are tan or grayish with a dark area in the center. Crawlers begin emerging in May and continue to emerge sporadically through September. Avoid using chemical pesticides to control this insect which will harm beneficial insects. If control is necessary, use horticultural oil when crawlers are present.

Keep algae growth down in your garden pond. Too much light and excessive nitrogen and nutrients create conditions for algae to flourish. Sources of nitrogen include fish and other animal wastes, uneaten fish food, and decaying plants. Provide your pond with good plant coverage to filter out excessive light and avoid overfertilizing the plants and overfeeding the fish that inhabit the pond.

Monitor your conifers for the presence of spider mites. Mites have piercing mouth parts and their feeding results in a stippled appearance on the foliage. Beat test plants by tapping the plant over a white sheet of paper. Look for small green, black, tan, or red mites about the size of a speck of pepper. More than 20 mites per beat may indicate serious damage. You can remove the mites with a jet of water from the hose or treat plants with horticultural oil. You can also buy predatory mites and release them to feed on the pest mites.