SYRi'HiDAK ()!' MAIM;. jor 



The Syrphidae may be distinguished readily from all tin- 

 other Diptera by the so-called false or spurious TV/;;, whirh 

 is a vein-like thickening of the wing-membrane between tin- 

 third and fourth longitudinal veins (radius 4 -5 and media 

 I -(- 2) and running through the anterior (radio-medial) cro>- 

 vein. It can be distinguished from the true veins by the fact 

 that it is not so clear-cut nor so deep in color and that it ends 

 freely without joining other veins. This false vein is present 

 in all but a very few Syrphidae and not found in the flies of 

 any other family. In the few cases where it is wanting 

 the fourth vein (media i-f-2) terminates in the third (radius 

 4+5) a considerable distance from the margin of the wing. 

 The following combination of characters will always distin- 

 guish them.* 



Head at least as broad as thorax. Front never excavated, often 

 swollen. Face excavated under the antenna? and projecting l>e!o\v, 

 or with a distinct tubercle near the middle. The antenna.- are three- 

 jointed with a dorsal arista or tapering into a terminal style. Ocelli 

 present, three. Tegulse of moderate size. Empodia not pulvilliform. 

 Bristles (macrochaetae) almost always wanting, never on the head 

 Second (radius 2-J-3) and third (radius 4+5) longitudinal veins 

 never forked; fourth longitudinal vein (media i-f-2) joins the third 

 before the margin of the wing. Three posterior cells ; the anal 

 (cubital) cell long, acutely closed before the border of the wing; 

 basal cells (radial and medial) large; bet-ice en the third ( radiu^ 

 4+5) a >'d fourth (media i-f-2) reins and nearly parallel -:cith them 

 there is a false or spurious vein nearly always present and charac- 

 teristic of the family. The post alar membrane.-, or squamae with 

 peculiarly-formed, forked and fan-like ciliation, and an elongate fringrd 

 filament-like projection, the plumula, from the upper margin of the 

 pteropleura beneath the >quamae (Vermin. 



How FLOWER-FLIES LIVE. 



Any one of these flies during its entire existence passes 

 through four quite different and distinct conditions or life- 

 stages: The egg; the larva ; the pupa ; and the adult. 



(i) The F-gg. The eggs of Syrphidae are placed, by tin- 

 parent fly in many different kinds of places, depending <>n the 

 species, but generally in such a situation that the young when 

 they hatch may easily Mud at hand an abundance of the par- 



*Williston (62. p. xxvi). 



