The first Pollinator Week was observed in 2007 in America after the Senate’s unanimous approval of a resolution that acknowledged the week as a necessary step in recognizing the urgent issue of declining pollinator populations. Pollinator Week is an annual event celebrated all over the world in the last full week in June. The event is organized and conducted in support of pollinator health by the Pollinator Partnership.
The week is observed as an international celebration to protect the ecosystems that sustain all pollinators – be they bees, flies, wasps, beetles, moths, butterflies or hummingbirds.
As we continue this weeklong event, let’s focus on one that most of us probably do not think of as a pollinator of flowering plants – flies.
Flies are two-winged insects and principally differ from bees in that bees have two pair of wings. Unlike honeybees, flies don’t need to carry pollen and nectar back to a hive. They simply visit flowers to sip on the nectar themselves. Carrying pollen from one flower to the next is incidental. But, since these airborne busybodies require frequent refueling throughout their daily excursions, their incidential pollen distribution during these numerous daily visits all sum up as to why flies are second only to bees in terms of importance for pollination.
A recent analysis of crop species found that flies visited 72% of the 105 crops studied (bees visited 93%). In some cases, flies can provide more consistent pollination in early spring than bees, likely because they are often active at cooler temperatures. (SOURCE: R. Rader, Cunningham, S.A, Howlett, B.G. and D.W. Inouye. “Non-Bee Insects as Visitors and Pollinators of Crops: Biology, Ecology and Management” Annual Review of Entomology. 65:20.1–20.17 (2020))
Flowers that are typically pollinated by flies are:
- pale and dull to dark brown or purple,
- sometimes flecked with translucent patches,
- characterized with a putrid odor, or
- shallow, but may be funnel-like or complex and trap-like.
The mouth parts of flower flies vary between species, giving different species access to nectar in different shapes of flowers.
The mouth of a typical flower fly is essentially an extendible sponge that can mop up either nectar or pollen that enables them to feed on shallow flowers.
Some species of flower flies have a modified mouth that forms a narrow tube that enables them to feed at tubular flowers.
Photo Credit: Beatriz Moisset.
When approaching a plant, some flies exhibit a characteristic flight pattern: they abruptly stop and hover in front or above a flower and can similarly abruptly change their position or direction and resume flight. This trait is the reason for their common name of hover flies, which are members of the family Syrphidae. Watch a short video.
Photo Credit: E. Beers,
http://s3.us-west-2.amazonaws.com/treefruit.wsu.edu/wp-content/uploads/2021/03/11121439/OPM_Syrphid04.jpg
Syrphid flies are among the most colorful and conspicuous flies found around flowers. Of the nearly 900 species in North America, most have yellow-and-black stripes and are excellent mimics of wasps or bees. While flies lack a stinger, their similar appearance to those that do makes birds and other potential predators avoid them.
Today, take a moment to stop and watch these insects endlessly buzzing about and acknowledge their surprisingly important contribution in pollinating so many plants that we humans rely upon for food. Please check out Pollinator Week and Pollinator Partnership for brochures, resources, and suggested activities to learn how each of us can help ensure that these important pollinators will forever be part of our world.
If you happen to be enjoying a chocolate as you read this, you may find this post to be a particularly interesting quick read. Enjoy!
Curious By Nature 