By Joan McIntyre, Extension Master Gardener
Pollinators provide an essential ecological service by moving pollen around so that plants can reproduce and incidentally provide seeds and fruit that feed people and many animals. Pollinators and insects in general are under threat due to industrial-scale agricultural practices, climate change, use of pesticides, and loss of habitat. While many causes are beyond our immediate control, we can move away from conventional landscape practices emphasizing extensive lawns with a few, mostly non-native foundation plants that contribute to a hostile environment for pollinators.
Homeowners have an opportunity to restore native habitat for pollinators, birds, and other wildlife. If only half of the 40 million acres now devoted to lawn were converted into more natural landscaping, an area larger than the combined acreage of most major national parks could be transformed, creating what Doug Tallamy is calling Homegrown National Park.[1] Adding even just a few flowering plants will make your yard more inviting to pollinators.
Invite Them In
Native plants are an essential requirement for supporting pollinators. While many non-native plants can be a good source for pollen, researchers have found that pollinators prefer native plants.[2] More importantly, pollinators have co-evolved with native plants and many require a specific plant species to reproduce. The relationship between milkweed (Asclepias spp.) and monarch butterflies is well known. The pawpaw tree (Asimina triloba) is the host plant for the zebra swallowtail butterfly and pussytoes (Antennaria plantaginifolia), and New York ironweed (Vernonia noveboracensis) are hosts to the American lady butterfly. Several native bee species require pollen from goldenrod (Solidago spp.) to feed their young. Native oak (Quercus spp.) and cherry (Prunus spp.) trees are powerhouses when it comes to supporting butterflies and moths, serving as hosts to caterpillars of 513 and 390 species of butterflies and moths respectively.
A pollinator garden should include a diversity of native trees, shrubs, and perennials that provide blooms from early spring through fall. An appealing space that will keep pollinators happy should also:
- Include flowers of varying sizes and shapes to attract many different pollinators. Small bees in particular favor plants with many small flowers such as Joe-pye-weed (Eutrochium dubium) and clustered mountain-mint (Pycnanthemum muticum) while bumblebees can access larger flowers such as wild blue indigo (Baptisia australis) that smaller bees cannot. Hummingbirds favor trumpet-shaped flowers such as coral honeysuckle (Lonicera sempervirens) and cardinal flower (Lobelia cardinalis)
- Include flowers of varying colors. Bees are most attracted to purple, yellow, and white flowers while butterflies and hummingbirds gravitate to red flowers.
- Group plants of the same species together to make gathering nectar and pollen easier as many pollinators, particularly bees, prefer to forage on the nectar of one species during a single outing.
- Avoid cultivars of native species that have changed the color or shape of the flower, such as double-flowered cultivars of the native coneflower (Echinacea purpurea), as they may be less attractive or accessible to pollinators.
- Wherever possible, remove nonnative, invasive plants such as Japanese holly (Ilex crenata), heavenly bamboo (Nandina domestica) and Japanese barberry (Berberis thunbergii) as well as ground covers such as English ivy (Hedera helix) and creeping liriope (Liriope spicata) that offer little of value for pollinators and are pushing out native plants in our natural areas.
Provide Water and Shelter
Like all living things, pollinators need water. Adding a few rocks in your birdbath will provide insects with a place to perch. Water should be changed every few days to prevent spread of disease and to control mosquitoes. You can also create a puddling space with sand and mud in a shallow dish on the ground to provide water and minerals for butterflies. A flat rock in a sunny spot offers a basking area for butterflies to sun themselves to warm their wing muscles so they can fly.
Including trees and shrubs in your yard will offer shelter for many insects. In addition, 70 percent of native bees are ground nesting and benefit from areas of well-drained soil in sunny locations with little or no mulch. Other bees burrow into wood so leaving brush piles, large branches or logs, or even the trunk of a dead tree will provide shelter for insects and other wildlife. Leaving leaf litter in your garden beds and waiting until spring to cut back native perennials and grasses will protect overwintering insects and provide winter food for birds. When cutting back in the spring, leaving 12 to 18 inches of stalks with hollow or pithy cores will support overwintering bees during the following winter. If you want to include bee nesting boxes you should put out several smaller ones in various locations rather than a large box with many nesting spaces to limit the spread of disease that could occur in a crowded space.
Make Your Yard Safe
Most importantly, you should limit the use of pesticides. Sprays such as those used for controlling mosquitoes are non-selective and will kill any insect that comes into contact with the sprays. Spraying during daytime when pollinators are active is particularly harmful. Moreover, residual chemicals from these sprays can remain on plants and flowers for hours or days afterward. There are less harmful and more effective ways to protect yourselves from mosquitoes, such as using repellants and eliminating standing water. You should also avoid using systemic pesticides such as neonicotinoids as the insecticide can be absorbed in the plant tissue and transported to nectar and pollen. While limited, there is emerging research that these chemicals, even in relatively small doses, can undermine the health of pollinators.[3]
Finally, try to limit outside lighting at night to protect nocturnal insects who may be attracted to or confused by the lights. Motion-detection sensors on outdoor lights can provide the security and light when you need it. In addition, research indicates that LED lights attract fewer insects than traditional incandescent lights.[4]
Each of us has an opportunity to support pollinators. Making our yards an oasis for pollinators can add joy to our lives through the flitting of butterflies, buzzing of bees, and the chirping of birds attracted to the insect life. Even a container or two on a balcony can bring nature to our doorstep. Encourage your neighbors to adopt these practices and if you belong to a Home Owners Association you can speak out in support of a pollinator friendly landscape.
Related Articles and Publications
Photo courtesy of Plant NOVA Natives
- Insects Make My Food and . . .
- Pollinators Under Threat
- Protecting Yourself From Ticks … Without Harming Pollinators
- Protecting Yourself From Mosquitoes … Without Harming Pollinators
- Tried and True Native Plant Selections for the Mid-Atlantic
Footnotes
[1] Tallamy, Douglas, Nature’s Best Hope: A New Approach to Conservation that Starts in Your Yard, Timber Press, 2020
[2] Annie White, “Creating a Pollinator-Friendly Landscape.” University of Vermont, Department of Plant and Soil Science, https://pss.uvm.edu/ppp/articles/pollinatorprac.html
[3] Arce, Andres N., Thomas I. David, Emma L. Randall, A. Ramos Rodrigues, T.J. Colgan, Y. Wurm and R.J. Gill. 2016. “Impact of controlled neonicotinoid exposure on bumblebees in a realistic field setting.” Journal of Applied Ecology. https://doi.org/10.1111/1365-2664.12792.
[4] Wakefield, Andrew, Moth Broyles, Emma L. Stone, Gareth Jones, Stephen Harris. 2016. “Experimentally comparing the attractiveness of domestic lights to insects: Do LEDs attract fewer insects than conventional light types?” Ecology and Evolution. https://doi.org/10.1002/ece3.2527.