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Genus Toxomerus

Syrphid Fly - - Lateral - Toxomerus marginatus - female Syrphid Fly - Toxomerus marginatus - female Syrphid Fly - Toxomerus politus Small fly - Toxomerus marginatus Syrphid Fly - Toxomerus marginatus Unidentified flying insect with bee-like marking - Toxomerus politus Syrphid - Toxomerus jussiaeae Syrphid - Toxomerus marginatus - male
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Aschiza")
Family Syrphidae (Syrphid Flies)
Subfamily Syrphinae
Tribe Toxomerini
Genus Toxomerus
Explanation of Names
Toxomerus Macquart 1855
From Greek toxon 'bow' + meron 'thigh' (refers to the bow-shaped hind femur)
Numbers
13 spp. in our area(1)
Size
5-13 mm
Identification
Pattern on abdomen is characteristic(2); look for a v-shaped notch on the back margin of the eye.
In identifying the most common eastern species, consider the margin of the abdomen. If continuously yellow (sometimes narrowly so) you've got T. marginatus. If it is alternating black and yellow because the dark horizontal bands extend all the way to the edges, T. geminatus (scutellum dark with sharp yellow border) or T. politus (scutellum light). --Steve Pelikan
Guide to common spp.:

Further south, esp. in Florida, there are more species and identification from images is much more difficult (perhaps impossible)
Colors vary with overall temperature during pupation: if it was hot, the yellow/orange increases and the background becomes lighter, but if it was cold, the dark/black increases and the yellow/orange becomes darker like the background.
"extremely diverse in the tropics with many, many undescribed species and over 100 described species. In Florida, there are 10 species of Toxomerus: T. arcifer, T. boscii, T. corbis, T. dispar, T. floralis, T. jussiaeae, T. geminatus, T. parvulus, T. politus and T. marginatus. It is necessary to see characters on the hind leg of the male, a good lateral view, and wing microhairs to identify Florida specimens to species." --Jeff Skevington
Range
Holarctic
T. marginatus: much of the US & so. Canada; common
T. geminatus: e. NA; common
T. politus: so. Canada to Argentina; uncommon
T. occidentalis: w. NA; common
10 spp. in Florida
Life Cycle
Eggs are laid singly on plants near aphids. Presumably late-instar larvae overwinter. Pupation is in soil cavities in spring; adults emerge in summer.(2)
Egg laying
See Also
Internet References
Works Cited
1.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. Canadian Journal of Arthropod Identification 23: 1-351.
2.National Audubon Society Field Guide to Insects and Spiders
Lorus and Margery Milne. 1980. Knopf.