Bee balm — a hummingbird, bee, and butterfly magnet.

Spring is upon us, and that means many of us will hit the garden centers and nurseries in search of plants and flowers to beautify our landscapes. The plants we choose to buy are of great importance. If we select only non-native species that have likely been treated with pesticides, we aren’t contributing to our local ecosystem, and we may be creating a habitat desert. If we include native plants, we will help sustain biodiversity and especially insect populations, which have been in steep decline over the past several decades.

Why should we be concerned about the disappearance of insects? They are a keystone species of both the plant and animal world. The world as we know it would not exist without them. Insects are:

• Our principal pollinators (bees, flower flies, butterflies, moths, wasps, and beetles) of both flowering plants, orchards, and agricultural crops
• A significant source of food in nature’s food web
• Efficient decomposers and recyclers of organic waste, which enrich the soil to spur new plant growth

Insects have co-evolved with native plants, and many of them rely on specific host plants during their developmental phases. Butterflies and moths exemplify host-plant dependency. While the adults may collect nectar and pollen from a variety of flowers, their immature caterpillars can only digest the leaves of specific host plants. Some examples are monarchs and milkweeds, spicebush swallowtails and spicebush, and skippers and grasses.

A monarch caterpillar on a milkweed.

Many other kinds of insects have host plant dependency, such as native “specialty bees” who collect pollen and resins from only one or two types of plants to feed their young and waterproof their nests. Even fireflies are dependent on host plants, though indirectly. Firefly larvae feed on snails that mainly eat plants in the aster family.

The number of insects is declining for many reasons: fragmentation of open space, pesticide use, and the preference for non-native ornamental plants over native ones. Loss of habitat leads to a loss of host plants. If insects cannot find their host plants where they live, they will not survive.

Natural Food Webs

Planting natives to boost insect populations benefits the rest of the food chain. All animals either eat plants (pollinated mainly by insects), or they eat insects directly, or they eat other animals that eat insects, or a combination of all three. Songbirds rely heavily on insect populations to raise their young. The parents must catch thousands of caterpillars to raise one clutch of hatchlings successfully. Baby birds cannot thrive on bird seed as it lacks the calories, fats, and protein needed for them to grow and fledge the nest as soon as possible.

Frogs, toads, box turtles, and garter snakes dine on insects, as do chipmunks, squirrels, raccoons, foxes, coyotes, and bears.

Native trees and shrubs not only serve as larval hosts for insects, they also bear fruits, berries, and nuts that support birds and wildlife. Acorns, hickory and beechnuts, as well as late-season berries, provide food during the cold months.

Most ornamental non-native plants are imported from Europe, central and southeast Asia, China, and Japan. While they enhance the beauty of the local parks and gardens, they don’t support local ecology. The Florida and Kousa dogwoods illustrate the contrast in ecological value of native versus non-native. The Florida dogwood (below) is a host plant for the spring azure butterfly. In contrast, the Kousa dogwood, a popular landscape plant originally from Asia, offers magnificent, showy blooms but hosts no North American butterfly species.

The Florida dogwood is a host and berry plant.

Where to Start?

It isn’t necessary to rip out every non-native species and start from scratch. The idea is to build on existing landscapes. By adding a few plants a year, we can increase the ecological value of our backyard habitats.

Pick a few perennial plants that bloom in succession from early to mid-spring, mid-spring into summer, and late summer into fall. This will ensure continuous bloom to accommodate different life cycles of insects. Some good choices are:

Anise hyssop, asters, bee balm, black-eyed Susans, butterfly weed, great blue lobelia, golden Alexander, goldenrod, Joe Pye weed, milkweed, mountain mint, New York ironweed, penstemon digitalis, purple coneflowers, violets, wild geranium, woodland phlox, woodland sunflowers.

Supplement these with herbs, such as fennel, mints, oregano, and parsley. While most herbs are not native, they do provide pollen and nectar and host butterfly and moth larvae.

Consider adding some annuals, such as cosmos, salvias, and zinnias, which attract bees and butterflies; and clumping grasses, like little bluestem and Pennsylvania sedge, which host several kinds of butterflies, moths, and grasshoppers.

Round out your habitat by adding any of these understory trees and shrubs:

American holly, Carolina allspice, chokecherry, coastal leucothoe, Florida dogwood, red osier dogwood, spicebush viburnums, willows, winterberry holly, witch hazel.

Woodland sunflowers bloom late summer into fall.

Another good reason to plant natives is that they are well adapted to local soils, weather, and growing conditions. They require little care and, once established, need little supplemental water.

Grupes House Garden Plans (NCLT’s New Headquarters)

A bountiful native habitat offers food, shelter, and a place for the current and future generation of pollinators, insects, birds, and wildlife to thrive. To this end, NCLT is creating a native plant habitat and demonstration garden at our new headquarters at Grupes House on Valley Road. We are collaborating with master gardener volunteers to recreate the walled garden below the house. The garden will feature native perennials, grasses, vines, understory trees, shrubs, herbs, and annuals that benefit a wide range of wildlife. The garden will be open to the public every day and serve as an educational site to inspire our community to embrace native plants and learn how to enhance the biodiversity of our backyard habitats.

Spicebush swallowtail on purple coneflower