Sunday, May 19, 2019

Pollinator of the Week: Flower Flies

Tachinid fly, photo courtesy of Beatriz Moisset
The two-winged insects (flies, gnats, mosquitos) is a very large and varied group. Many of them specifically visit flowers, such as the Syrphid flies or flower flies. They are not as hairy as bees nor as efficient at carrying pollen, but some are still good pollinators. The USDA Forest Service provides the following information about Fly Pollination.

Syrphid fly, a bee mimic, photo courtesy Beatriz Moisset

Flowers that are pollinated by flies typically:
  • Are pale and dull to dark brown or purple;
  • Are sometimes flecked with transparent patches;
  • Have a putrid odor;
  • Do not have nectar guides;
  • Produce pollen;
  • Have flowers that are funnel-like or are a complex trap.

Some flies, such as Syrphids, masquerade as bees and wasps. However, the pollinating flies can be distinguished with a sharp eye. The flies only have one pair of wings while bees and wasps have two. Bee flies, Bombylids, are robust and extremely hairy, and some have tongues as long as their bodies.

Dogbane, a common pink flowered shrubby herb, is a pollinating fly’s worst friend. When long-tongued pollinators visit the flowers of Dogbane, their tongues become coated with a pollen and cement-like mixture from the flower. Flies and other lightweight pollinators often become glued to the flower and die a slow death from starvation.

Next time you see an odd-looking “bee” visiting a flower, look more closely. It might just be one of the fly pollinators!