Pollinator of the Month: Bee Flies (Bombyliidae)
Bee flies (Bombyliidae) are a group of flies that belong to the order Diptera, though they mimic the appearance and behaviour of bumble bees. They have only one pair of wings, large eyes, and short antennae like other flies. Though they also have a fuzzy appearance with hairs covering their bodies. They also make a buzzing noise when they fly.
The bee fly has more in common with bumble bees than just sharing a similar appearance. Both bee flies and bumble bees compete for similar floral resources. Bee flies are sometimes reported to be less effective pollinators as they have long stiff tongues that allow them to access nectar from flowers without landing on them. Bee flies likely remain hovering near flowers while extracting nectar to help them avoid predation, as they can more quickly fly away if they did not land on the flower. However, it is unclear whether they are actually less effective pollinators as static electricity pulls pollen towards bee flies while they are pollinating flowers. Bee flies also visit flowers more frequently than bumble bees, which could actually make them a more effective pollinator. More research is likely required to fully understand the effects flies, including bee flies, have on pollination as previous pollination studies have typically focused only on bees, butterflies, and hoverflies as pollinators.
Bee flies are good fliers, as they can move fast, change direction quickly, and hover in the air. As previously discussed, hovering helps them avoid predation but it also helps them parasitize bumble bees. Bee flies lay their eggs in the spring. They hover over bare ground, where the bumble bees dig their nests, and drop their eggs into the openings of bumble bee nests. The fly larvae hatch and feed on the food supply that was meant for the developing bumble bees, or on the developing bumble bees themselves. The larvae pupate and stay inside the nest until the next spring, when they emerge as adults.
Bee flies are widely distributed throughout North America. In Calgary, member of the bee fly family that have been observed interacting with flowers include tawny-tailed bee fly (Villa fulviana), Poecilanthrax tegminipennis, Woolly Bee Flies (Systoechus sp.), Anastoechus sp. , Poecilanthrax alcyon, Greater bee flies (Bombylius sp.), Poecilognathus sp., and sinuous bee fly (Hemipenthes sinuosa). The tawny-tailed bee fly, Poecilanthrax tegminipennis, Poecilanthrax alcyon, and sinuous bee flies are native to Canada.
The tawny-tailed bee fly is pictured below.
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