SYRPHIDAE OF MAINE. 201 



The Syrphidae may be distinguished readily from all the 

 other Diptera by the so-called false or spurious vein, which 

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

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

 i-j- 2) and running through the anterior (radio-medial) cross- 

 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 1+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 antennae and projecting below, 

 or with a distinct tubercle near the middle. The antennas 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+3) and third (radius 4+5) longitudinal veins 

 never forked; fourth longitudinal vein (media 1+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; between the third (radius 

 4+5) and fourth (media 1+2) veins and nearly parallel with them 

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

 teristic of the family. The post alar membranes or squamae with 

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

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

 pteropleura beneath the squamae (Verrall). 



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. 



(1) The Egg. The eggs of Syrphidae are placed by the 

 parent fly in many different kinds of places, depending on the 

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

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



*Williston (62, p. xxvi). 



