University of Vermont
Department of Plant and Soil Science

gmg logoSummer News Articleline


Annie White, Research Assistant and
Leonard Perry, Horticulture Professor Emeritus
University of Vermont

Interest in gardening to support pollinators is at an all-time high. Books and websites are brimming with information about the importance of pollinators, as well as how to create gardens and landscapes rich with the floral resources that pollinators need. However, discussions about the full breadth of pollinators attracted to pollinator gardens are harder to find. Monarch butterflies and honeybees get a lot of attention but, in fact, they are just two of the thousands of species of pollinators in the U.S. that benefit from pollinator-friendly landscapes.

Bees are by far the most important pollinators worldwide, visiting and pollinating flowers more frequently than other pollinator groups. Bees also are very effective pollinators, helping to move pollen from one flower to another, fertilizing the plant.  They feed on flower pollen and nectar during all stages of their life. Most female adult bees have specialized pollen-collecting structures and spend much of their time collecting pollen from flowers to feed their young. Furthermore, bees are covered in a dense coat of feathery hairs that effectively catch and carry pollen grains.

There are nearly 20,000 bee species in the world, but just one species, the European honeybee, lives in hives and is managed commercially by humans. We rely on honeybees to pollinate large crops like almonds, apples, and blueberries and, of course, to make honey. In addition to the flowers of fruits and vegetables, honeybees favor nectar- and pollen-rich flowers like milkweeds (Asclepias spp.), hyssops (Agastache spp.), and clovers (Trifolium spp.).

Here, in North America, we have about 4,000 species of wild bees. They don’t make honey like the honeybee, but they are extremely important for the pollination of food crops and wild plants. Among the most recognizable of our wild bees and the most proficient pollinator is the bumblebee (Bombus spp.). Bumblebees use buzz pollination, also known as sonication, to release pollen from a flower’s anthers. If you watch a bumblebee pollinating a tomato flower, you will see the bee clinging to the anthers with their mouthparts or forelegs and vibrating their flight muscles to release the pollen. Bumblebees are big and strong, allowing them to pry their way inside flowers such as wild indigo (Baptisia spp.), great blue lobelia (Lobelia siphilitica), and bottled gentian (Gentiana andrewsii), which other pollinators have difficulty penetrating.

Many other wild bee groups, large and small, can be seen foraging on the pollen and nectar of flowers. You might see sweat bees, who owe their name to their tendency to gently lap the salty sweat off gardeners while they work. Some sweat bees have eye-catching metallic green bodies. Like most small wild bees, they have a preference for small flowers, such as yarrow (Achillea spp.), or composite flowers comprised of many tiny florets, such as purple coneflowers (Echinacea purpurea).

Leafcutter bees are just one more group of wild bee that is easily spotted in the garden. They are unique in several ways. Unlike most bees that carry pollen on their hind legs, leafcutter bees carry pollen in a band of hairs on the underside of their abdomen. Secondly, as their name implies, leafcutter bees cut pieces of leaves to line their nests. The plant material provides waterproofing and antimicrobial properties. You will find leafcutter bees feeding on a variety of flowers including tickseed (Coreopsis spp.) and black-eyed susan (Rudbeckia spp.) You also will find them building nests in old hollowed stems of sumac, elderberry, and raspberry.

Behind bees, flies are the second-most frequent visitors to flowers, with the most common of all flies being syrphid flies. Nearly all of the 6,000 species of syrphid fly adults worldwide consume nectar, and most species also consume pollen. Some stingless syrphid flies mimic the appearance of stinging bees and wasps with black, white, and yellow markings.

Butterflies and moths are eye-catching and fun to see in the garden, but they are weak pollinators compared to other insects. With few exceptions, butterflies and moths are nectarivorous, meaning they only consume nectar and no pollen. Therefore, any movement of pollen by butterflies and moths is an involuntary outcome of their nectar feeding. Butterflies and moths have a long sucking mouthpart, called a proboscis, to suck up nectar. It is particularly useful for reaching the nectar in long tubular flowers like beebalm (Monarda spp.). Butterflies also prefer to forage on composite flowers such as coneflowers (Echinacea spp.) and asters (Symphyotrichum spp.), which provide a nice surface to rest on while they feed. Many moths and butterflies also use plants as hosts for rearing their young. The monarch butterfly is an example of a specialist butterfly that uses a single plant genus, milkweeds (Asclepias spp.), as a host plant.

A huge diversity of less-frequent pollinator visitors are also observed in pollinator gardens, including beetles, parasitoids and predatory wasps (which, believe it or not, are great insects to have as they are nature’s control agents for pests we don’t want), ants, and hummingbirds. By planting a diversity of flowering plants that vary in size, shape, color, and bloom time, you will be sure to attract an amazing diversity of pollinators to your garden.

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