By Silvia Strobl, Master Gardener

You may know that native bees are the most important of our native pollinators, but which insects are the second most important pollinators of food crops and native wildflowers?

Perhaps you’ve never heard of flower flies? Visiting flowers more often and moving more pollen than pollinators such as butterflies, flower flies range in size from less than 1/4 inch long to more than 3/4 inch long, but pollinate at least 72% of global food crops and about 70% of wildflowers (Pollinator Partnership, 2024).

Maybe you have mistaken their strongly contrasting black and yellow bands on the abdomen for a bee or a wasp? Their colouring mimics that of these stinging insects—an evolutionary development known as Batesian mimicry. The English naturalist, Henry Walter Bates, came up with this term for harmless species that take on the physical traits of dangerous or bad-tasting species. So although hover flies lack a stinger, their colouring imitates the warning colours of bees and wasps that do have stingers, thereby offering protection by deceiving predators.

The larvae of flower flies are stellar pest managers, consuming aphids, leafhoppers, mealy bugs and thrips. In fact, one larva can eat up to 400 aphids over its two to three week development!

Females lay hundreds of eggs, depositing each tiny white egg singly on leaves or shoots near colonies of aphids. The larvae hatch in two to three days and resemble small legless maggots,  ranging in colour from creamy-white to green or brown (Mahr 2025).

Four common flower flies that I have observed and photographed in my garden, and whose identity has been verified by experts on iNaturalist, are shown and described in the following. Lists of flowers visited are from Skevington et al 2019).

There are 416 known flower fly species in eastern North America (Skevington et al. 2019). So I hope to observe and photograph at least a few more species on flowers in my garden this season! Nearly all flower flies can readily be identified by their:

• Large heads with large forward-facing eyes that often fuse together. Bees have kidney-shaped eyes on the side of their heads.
• Stubby, short antennae as opposed to the long antennae that bees have
• Only 2 wings compared to 4 wings for bees and wasps (Erikson 2020)
• A “false” vein in their wing venation i.e., a vein that is not joined to any others

From: https://ipm.ucanr.edu/PMG/S/I-DP-SYRP-KC.003.html#gsc.tab=0

How do you attract these super pollinators and pest managers to your garden?

1. Flower flies prefer white and yellow flowers that are open and have easily accessible pollen and nectar, for example the disc flowers in the daisy (or Asteraceae family), but they also use orange, pink, purple, and blue daisy-like flowers. According to a recently published book about the flower flies of northeastern North America, native plants are essential to supporting a diversity of flower flies (Skevington et al. 2019). Non-native plants that attract flower flies include: Queen Anne’s lace, wild mustard, sweet alyssum, coriander, dill, broccoli, kale, lettuce, mustards, dandelion, plums and cherries (Mahr, 2025, Pollinator Partnership 2024).
2. Don’t use pesticides since they can kill both the larvae and the adult flower flies.
3. To give the larvae something to eat, tolerate some level of aphids and other pests in your garden.

Don’t be surprised if by doing these things you suddenly start seeing flower flies in your garden. Also known as hover flies, you may even observe their darting back and forth flying behaviour i.e., when males hover in the open hoping to attract a female, or when males of some species defend a territory.

Flower flies are some of the most beneficial insects you can have in the garden so invite them in by planting the annual non-native and native flowers they prefer.

Literature Cited

Erikson, B. 2020. Flower flies: insects with a “PR problem”. Wild Pollinator Partners.

Mahr, S. 2025. Hover, Flower or Syrphid Flies (Syrphidae). Wisconsin Horticulture, Division of Extension.

Pollinator Partnership. 2024. Flower flies—masters of disguise. 2-pages.

Skevington J.H., M.M. Locke, A.D. Young, K. Moran, W.J. Crins and S.A. Marshall. 2019. Flower Guide to the Flower Flies of Northeastern North America. Princeton University Press. 512 pp. (Note: all 6 authors are Canadians from Ontario).