Species of Sphaerophoria have face and scutellum yellow in background colour; anterior anepisternum bare; postpronotum bare; scutum with a sharply defined yellow lateral vitta; abdomen unmargined; subscutellar fringe absent or nearly so on at least median 1/3, present but sparse laterally; metapleuron bare ventrad to spiracle; male genitalia extremely large, globose; tergite 9 as wide as abdomen.
Vockeroth (1969) diagnosed the genus: Very slender, small to medium-sized flies with extremely large hemispherical male terminalia, almost always with bright yellow markings on head, thorax, and abdomen but rarely almost entirely black. Length 5.9 to 10.8 mm.
Eye bare. Face yellow, often with distinct black median vitta, entirely black only in nigra Frey. Face somewhat protruding below, in profile area between antennae and apex of tubercle oblique and scarcely concave and area below tubercle receding only very slightly to anterior oral margin; oral opening about 2.2 times as long as broad. Usually thorax black with bright yellow lateral mesonotal vitta at least presuturally, scutellum bright yellow or rarely brownish on disc, and pleura with bright yellow markings; scutum and pleura entirely black only in nigra Frey. Subscutellar fringe usually absent on median fourth to half of scutellum and very short and sparse laterally, rarely entirely absent. Dorsal and ventral katepisternal pile patches distinctly separated but the former usually triangularly extended ventrally about 3/4 of the distance from dorsal to ventral margin of katepisternum. Metasternum usually with a few hairs, rarely entirely bare. Metafemur in scripta (L.) with posteroventral piles short, stiff, black, and setulose in male and similar, but much weaker, in female; legs otherwise unornamented. Abdomen slender, unmargined, in the male parallel-sided and sometimes extending well beyond the wing apices, in the female usually slightly broadened at mid-length and extending at most very slightly beyond wing apices. Tergum 5 of male with rounded posterior extension on right side. Abdomen entirely black only in nigra Frey, otherwise with yellow markings as follows: terga narrowly to broadly yellow laterally and sometimes posteriorly; terga 2 to 4 with narrow to broad, entire or divided, usually arcuate, transverse fascia which may not reach the lateral yellow margin; tergum 5 usually with yellow fascia extended forward to anterior margin of tergum and sometimes backward to posterior margin so tergum may have a pair of submedian yellow vittae or be mostly yellow with isolated black maculae; tergum 6 in female exposed, usually yellow with one median and a pair of posterior black maculae, sometimes with the maculae fused or only the median present; in male sometimes the black markings of terga as far forward as the second becoming red or orange so abdomen is mostly yellow-orange. Sternites yellow, without distinct markings (adapted from Vockeroth 1969: 132).