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Genus Eristalis

Drone Fly - Eristalis tenax - male Drone Fly - Eristalis tenax flower fly - Eristalis dimidiata Fly - Eristalis flavipes Is this a Eristalis dimidiata ? - Eristalis dimidiata Syrphid Flies Eristalis tenax  - Eristalis tenax - female Syrphid Fly - Eristalis tenax Fly - Eristalis dimidiata
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Aschiza")
Family Syrphidae (Hover Flies)
Subfamily Eristalinae
Tribe Eristalini
Subtribe Eristalina
Genus Eristalis
Other Common Names
Drone Flies (sometimes applied to E. tenax only), Rat-tailed Maggots (larvae of E. tenax)
Synonyms and other taxonomic changes
reviewed in(1)
Explanation of Names
Eristalis Latreille 1804
Latin eristalis, a kind of gemstone, maybe opal (likely what Latreille meant)
2 subgenera, with 20 spp. in our area(2) and ~100 total(3)
7-17 mm
Some species (e.g., E. tenax) resemble honey bees. Others are darker, less hairy, e.g., E. dimidiatus, E. nemorum.
Moderately to very hairy; head broader than high and about as broad or slightly broader than thorax; antennae short, inserted near middle of head, third segment longest ventrally, while dorso-apically it is shorter and rounded; arista generally long; eyes range from bare to pilose, holoptic to narrowly dichoptic in male; mesonotum short and compact, rather convex; scutellum without fringe; stigmatic cross-vein present, spurious vein generally distinct, marginal cell closed, third vein deeply bent into apical cell and ending well above apex of wing, anterior cross-vein at or near middle of discal cell; hind femora slender to moderately thickened and without spurs, spines, or teeth; tibiae nearly straight or moderately arcuate; abdomen generally with yellow and black markings.
Wing venation:

Key to species, courtesy of Martin Hauser:

For full-size version, click here.

Text key to species by Bill Dean under the image below:

Larva's anterior spiracles dark brown; prolegs with crochets in three rows with spicules gradually becoming smaller below
Holarctic, Neotropical, Afrotropical, Oriental(3); E. tenax is introduced from Europe
Fields, etc. with flowers
Mar-Nov in NC(4), Apr-Oct in MN
Adults take nectar. Larvae feed on small organisms in stagnant water.
Life Cycle
Larvae, at least of E. tenax, live in eutrophic water, have tail that serves as "snorkel" for breathing. They are called rat-tailed maggots.
Larva, puparium, female ovipositing
Eggs of E. tenax are occasionally swallowed by humans and the larvae live in the human intestinal tract, where they cause "myiasis". E. tenax sometimes emerges from carrion, closely resembles honey bee. This may account for the biblical story of honeybees nesting in a dead lion.
Print References
Hull F.M. (1925) A review of the genus Eristalis in North America. Part I | Part II Ohio J. Sci. 25: 11–43, 285-312
Works Cited
1.Eristalis (Diptera: Syrphidae) from America North of Mexico
Telford H.S. 1970. Ann. Ent. Soc. Am. 63(5): 1201-1210.
2.Key to the genera of nearctic Syrphidae
Miranda G.F.G, Young A.D., Locke M.M., Marshall S.A., Skevington J.H., Thompson F.C. 2013. Can. J. Arthropod Identification 23: 1-351.
3.Austalis, a new genus of flower flies (Diptera: Syrphidae) with revisionary notes on related genera
Thompson F.C. 2003. Zootaxa 246: 1-19.
4.Insects of North Carolina
C.S. Brimley. 1938. North Carolina Department of Agriculture.
5.Syrphidae of Ontario