Around 40% of the flowering plants in North America require insect pollination for reproduction, though at the mention of the word “pollinator”, most people probably picture the European honey bee (Apis mellifera). This is an important species relied on heavily in the agricultural industry; however, the honey bee is not a native insect to the US. It was brought to the eastern shores of North America by European settlers in the early 1600’s. Within 200 years honey bees had spread across the entire continent. Prior to their introduction, hundreds of species of insects native to North America could be found foraging and transferring pollen from flower to flower. Today, native insects still play a vital role in pollination.
Native Bee Families
A bumble bee (Apidae) is visiting on a cucumber flower (Cucumis sativus).
Justin Ballew, ©2017, Clemson University
Apidae (Honey Bees, Bumble Bees, Carpenter Bees, Squash Bees, and Blueberry Bees): Apidae is the largest family of bees and includes Apis melifera, as well as a number of other honey bee species, none of which are native to the US. Bumble bees are another largely familiar group of bees and is made up of around 50 native species. They are big, furry, and usually black and yellow. Bumble bees are good pollinators of certain crops, such as tomatoes, and are commonly kept by beekeepers for just that purpose.
Carpenter bees are similar in appearance to bumble bees, and it can be tricky to distinguish them apart. The easiest way to tell the difference is by looking at the abdomen. Bumble bees are hairy all over their abdomen; however, carpenters bees are almost hairless and appear glossy on their upper abdomen. While carpenter bees can be considered pollinators, they can also rob certain flower species of their nectar without transferring any pollen. The bee does this by cutting a slit with its mouthparts near the base of the flower and drinking the nectar without ever entering the flower. These are also the culprits that make their nesting sites by boring into wood, sometimes causing significant damage to structures.
Squash bees look similar to honey bees and begin foraging around sunrise before other bees are active. They are excellent pollinators of Cucurbita vegetables (squash, zucchini, gourd, and pumpkins), which they visit exclusively. Squash bees are considered to be much more efficient pollinators of squash than honey bees and account for the pollination of around 2/3 of the squash grown in the US. Squash bees are solitary bees that nest in burrows dug in the soil beneath the plants they will pollinate.
Southeastern blueberry bees are only active for a few weeks of the year and appear when members of the Vaccinium genus (blueberries, deerberries, and huckleberries) are in bloom. Blueberry bees spend less time visiting each individual flower and visit more flowers in a shorter amount of time than honey bees, making them more efficient pollinators of blueberries. Once they land on the flowers, they vibrate their bodies causing pollen to fall from the anthers. The pollen sticks to the bee’s body, which is transferred to other flowers.
Andrenidae (Miner Bees): These are solitary, ground nesting bees are mostly dark colored, although some species are metallic blue, yellow, and/or red. Miner bees are excellent pollinators of azaleas (Rhododendron spp.), and some species specialize in pollinating apples (Malus spp.). Miner bees create unique vibrations with their wings that shake clumps of pollen from the anthers. This pollen is transferred to other flowers as they forage. Honey bees are not able to shake the flowers in the quite same manner.
Colletidae (Plasterer Bees and Yellow-Faced Bees): This is a unique family of solitary bees that do not carry pollen on the outside of its body. Instead, they swallow pollen and carry it inside their crop. Some species nest in the ground, while others nest in stems and cavities of plants. These bees are not nearly as hairy as other bees and are sometimes confused for wasps. There are approximately 150 species in North America.
Halictidae (Sweat Bees): One of the larger families of bees with over 2000 known species, sweat bees vary greatly in appearance, but most are small and often metallic colored. They are important pollinators of apples, peaches, cherries, sunflowers, a number of other crops, and wildflowers. Sweat bees are mostly solitary bees; however, they are abundant and many may live in close proximity to one another. Some species are attracted to human sweat and may be annoying.
Megachilidae (Mason Bees and Leaf-Cutter Bees): This large family of bees has over 600 species in North America. They are different from other bees in the way they carry pollen. Instead of carrying it on their back legs, pollen is carried on the underside of the abdomen. Pieces of leaves and/or mud are used to construct their nests, usually located in wood cavities or hollow twigs. It is common to see neatly cut circular holes made by leaf-cutter bees in the leaves of plants.
A miner bee (Andrenidae) is foraging on a dandelion (Taraxacum) flower.
Justin Ballew, ©2017, Clemson University
A nearly perfectly circular hole was cut in a leaf by a leaf-cutter bee.
Justin Ballew, ©2017, Clemson University
Other Native Pollinators
A sphecid wasp is foraging on a bottlebrush flower (Callistemon sp.).
Justin Ballew, ©2017, Clemson University
Wasps: Wasps differ in appearance from bees by the absence of hair on their bodies, which generally makes them less efficient pollinators. They are primarily predators of other insects, although they will occasionally feed on nectar. The families Scoliidae, Sphecidae (mud daubers and thread-waisted wasps), and Vespidae (paper wasps, yellow jackets, and hornets) include many species that exhibit this behavior. In addition, there are a number of species of parasitic wasps that feed exclusively on nectar.
Flies: There are several families of flies, such as Syrphidae, Tachinidae, Bombyliidae, that forage on flowers and assist in pollination. Even male mosquitos (Culicidae), which lack the mouthparts necessary for biting humans, feed on nectar. There are also some plant families whose flowers are specifically adapted for fly pollination. These flowers tend to be darker in color and have unpleasant scents that smell similar to rotting flesh. The cacao tree (Theobroma cacao), from which chocolate is made, is perhaps the most notable example of a fly pollinated plant. Although not native to the US, midges in the families Ceratopogonidae and Cecidomyiidae are essential for pollination and producing cocao beans.
Beetles: Beetles are thought to be among the first insects to visit and pollinate flowers. Flowers pollinated by beetles are usually large, such as magnolias (Magnolia spp.) and water lilies (Nymphaeaceae), or in clusters like goldenrod (Solidago spp.) and spirea (Spiraea spp.). Some of the beetle families that can be observed foraging flowers include Chrysomelidae (leaf beetles), Curculionidae (weevils), Nitidulidae (sap beetles), and Mordellidae (tumbling flower beetles).
Butterflies: Many gardeners plant flowers specifically to attract butterflies. Typically, they are beautifully colored and offer aesthetic value, but butterflies are not nearly as efficient in pollination as bees. They do not vibrate the way bees do, nor do they fly as fast or visit as many flowers. Some of the most common families seen visiting flowers include Papilionidae (swallowtails), Nymphalidae (brush-footed butterflies, including the monarch), Hesperiidae (skippers), and Pieridae (whites and sulphurs).
Moths: Moths are very similar to butterflies. However, moths feed mostly at night, while butterflies feed during the day. As a result, they often go unnoticed. An exception is the family Sphingidae (spinx moths), which has a number of species that fly during the day. Known as clear-winged sphinx moths or hummingbird moths, they are very hairy and are often black and yellow like bees. They are easily confused for bees because they typically do not sit still for us to get a good look at them.
Non-Insect Pollinators: Many other creatures also play a role in pollination. Hummingbirds, such as the ruby throated hummingbird (Archilochus colubris), are frequently observed collecting nectar in the Eastern US. They love brightly colored flowers and eat their weight in nectar every day. Bats can also be important pollinators in some parts of the world, though not so much in the US. They fly and visit flowers at night. There are two species of nectar feeding bats in the US (Choeronycteris mexicana and Leptonycteris curasoae), but these bats are only found in western states like Texas, Arizona, New Mexico, and California. Slugs and snails are another unusual example of non-insect pollinators in the US. They certainly don’t contribute as much as insects, though every little bit helps.
A leaf beetle (Chrysomelidae) is visiting a sunflower (Helianthus spp.).
Justin Ballew, ©2017, Clemson University
An Eastern tiger swallowtail (Papilionidae) is visiting a buttonbush (Cephalanthus occidentalis).
Justin Ballew, ©2017, Clemson University
Originally published 01/18
