Hover flies (Eristalis tenax) are the most familiar syrphid flies. They are easily confused with honeybees (especially the males, or drones) when seen browsing on flowers in early spring or late fall. The larvae grow in polluted water, breathing through a long retractable tube that they use like a snorkel. They are called rat-tailed maggots because of this appendage.
If one had to choose a typical syrphid fly, in terms of appearance, the Syrphus ribesii would take the prize. These very common, average-sized flies are black and yellow. The males often fly in groups and do not feed. The females, like those of several other species belonging to genus Syrphus, prefer honeydew to nectar as a sugar source.
Syrphid flies in genus Microdon have an odd association with ants. The adults so closely resemble bees that they have false pollen baskets on their hind legs, but the larvae develop inside ant nests. The larvae, which look like slugs or molluscs, feed on the ant eggs, larvae and nymphs until they become adults. Strangely enough, the ants tolerate their presence inside the colony.
There are more than 6,000 species of syrphid flies around the globe, some 900 of them in Canada and the United States. Because they are so popular with insect enthusiasts, syrphid flies are some of the best-known groups of flies.
Syrphid flies don’t sting or bite.