Black-and-red syrphid

Description:

This pretty little syrphid fly, Chalcosyrphus piger (or pigra), was displaying and/or basking from the railing of my deck. These flies are said to be "hilltoppers", that is, they gather at high places for mating, with males tending to stake out territories. These flies are all dark except for the bright red abdomen and are said to be Batesian mimics of spider wasps with this pattern, esp. genus Astata. Length about 10 mm.Identification as to species level in this genus is tough, but see the BugGuide page linked above, and especially this plate from Syrphidae of Ontario. Note short appressed (not erect) hairs on thorax, tarsi all black. Also, this is a common species listed in the North Carolina State University entomology collection, so I think I've got this one.