Eristalis
Guides
Eristalinae
Drone Flies and Allies
Eristalinae is a subfamily of hoverflies (Syrphidae) comprising approximately nine tribes and notable for exceptional Batesian mimicry of bees and wasps. Adults are important pollinators, while larvae exhibit the greatest habitat diversity among hoverflies, occupying aquatic environments, decaying organic matter, sap runs, and even wasp nests. The subfamily includes the well-known drone fly (Eristalis tenax), whose larvae—called rat-tailed maggots—possess an extendable posterior breathing siphon.
Eristalis brousii
Hourglass Drone Fly
Eristalis brousii, commonly known as the hourglass drone fly, is a hoverfly species first described by Samuel Wendell Williston in 1882. The species has experienced severe population decline across North America following the introduction of the European congener Eristalis arbustorum near Toronto around 1885. As of 2019, it persists only along the lake margin of Hudson Bay in Northern Canada, making it one of the most geographically restricted hoverflies on the continent. Like other Eristalis species, adults are pollinators while larvae develop as aquatic filter-feeders.
Eristalis obscura
Dusky Drone Fly
Eristalis obscura, commonly known as the dusky drone fly, is a species of syrphid fly first described by Loew in 1866. It is widespread across northern North America and extends eastward through Europe to Siberia. The species exhibits the characteristic rat-tailed maggot larval form, with aquatic larvae that function as filter-feeders. Like other members of the genus Eristalis, adults are likely bee mimics, though specific documentation of this behavior for E. obscura is limited.
Eristalis transversa
Transverse-banded Drone Fly, Transverse Flower Fly
Eristalis transversa is a hoverfly in the family Syrphidae, first described by Wiedemann in 1830. Adults are bee mimics, displaying Batesian mimicry of stinging Hymenoptera. The species is common in eastern North America and is frequently observed visiting flowers for nectar and pollen. Like other Eristalis species, adults are important pollinators, though specific larval habitat for this species has not been documented.