Flying high
Syrphid fly and white-mouth dayflower (Commelina erecta).
Do a little quick research, and you’ll find that animals are responsible for pollinating about 90% of all flowering plants and about 30% of the crop plants that land in our grocery stores and kitchens. Think corn, berries, beans, avocado and chocolate.
All good stuff, right? And all possible thanks to not just the birds and bees, but also beetles, moths, wasps, small mammals, ants, and flies (Order: Diptera). The order Diptera, with some 17,000 fly species, has its roots in the Greek term for “two-winged,” and the name dates back to Aristotle, who noted that flies, unlike typical four-winged insects, have just two wings, according to Bug Guide. Those thousands of species come in many forms, including house flies, mosquitoes, horseflies, hover flies and midges.
In a recent analysis, researchers estimated that the world’s 105 most widely planted food crops that benefit from insect pollination are worth some $800 billion a year (Smithsonian article, March 2021). The researchers also found that flies were the most important pollinators after bees, visiting 72% of those 105 crops.
Often considered simply pests that bite and buzz us when we’re trying to enjoy the great outdoors, flies are obviously super beneficial to ecosystems.
For example, some mosquitoes pollinate orchids, including Habenaria spp. (USFWS). And if it weren’t for midges – which are tiny flies in the same family (Ceratopogonidae) as those horrible biting “no-see-ums,” the cacao flower would not get pollinated and we would not have chocolate, according to Pollinator Partnership.
“The cacao flower, while only about the diameter of a nickel, is complex in design and behavior, necessitating a special kind of animal to pollinate it. Recent studies in cacao plantations indicate that midges, tiny flies that inhabit the damp, shady rain forest, are the only animals that can work their way through the complex cacao flower and pollinate it,” the organization writes in its paper, “Chocolate’s Sweet Little Secret.”
Pollinator Partnership says plants pollinated by the fly include the American pawpaw (Asimina triloba), dead horse arum (Helicodiceros muscivorus), skunk cabbage (Symplocarpus foetidus), mango (Mangifera indica), and members of the carrot family like Queen Anne’s lace (Daucus carota).
Some flies are important as generalist pollinators, hitting a variety of plant species. The long-tongued flies, such as Syrphids and Bombylids, feed on the same flower types that bees do, and many of these flies resemble bees, as well. Short-tongued flies feed on flowers that imitate other fly food sources. The flowers of these plants, including Dutchman’s pipe (Aristolochia spp.) can temporarily trap a fly inside the flower while it feeds, for example, causing it to get well-covered in pollen before finally flying away. Carrion flies are attracted to putrid odors, and some plants that attract these flies are jack-in-the-pulpit, trillium and some orchids.
According to The Pollinator Partnership/North American Pollinator Protection Campaign’s “Selecting Plants for Pollinators” brochure, research shows that flies primarily pollinate small flowers. This makes sense, considering most flies are tiny themselves. The brochure also states that a pollinator study by the National Research Council indicates “that flies are economically important as pollinators for a range of annual and bulbous ornamental flowers.”
As we continue our Pollinator Week exploration, tomorrow we’ll take a look at that most iconic of pollinator – the busy bee.
By Laura Bennett-Kimble, Florida Native Plant Society member-at-large
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