According to new study from Washington State University, the syrphid fly, a small bee impostor, may be a significant benefit to some gardens and farms.
Flies accounted for around 35% of 2400 pollinator visits to flowers in urban and rural farms in Western Washington, according to an observational study. The majority of the flies were black-and-yellow-striped syrphid flies, commonly known as hover flies. Flies were the only pollinators found on a few plants, including peas, kale, and lilies. Bees were still the most prevalent, accounting for approximately 61 percent of flower visits, but other insects and spiders made up the rest.
Syrphid flies' bee-like coloring presumably help them escape predators frightened of being stung, but they are real flies with two wings, not four like bees. Olsson, a WSU post-doctoral fellow and lead author of the study published in Food Webs, noted that the flies may have extra benefits for plants since they devour pests like aphids as juveniles. They have the ability to transport pollen in the same manner as bees do when they drink nectar and visit flowers, albeit less deliberately than bees, who collect pollen to feed their young.
Plants, pollinating insects, and spiders were studied on 19 rural farms and 17 urban farms and gardens along the Interstate 5 corridor in Western Washington for the study. Over the course of two years, they performed six independent surveys. In addition to bees and syrphid flies, they recorded visits from wasps, lacewings, spiders, and butterflies, dragonflies, beetles, and ants, among other arthropods.
The lesson for small farm owners: don't swat the flies!