SYRPHIDAE OF MAINE. 247 



slightly branched, for the most part rather short, sometimes long, from 

 10 to 15 radiating from each body. 



Larva (Fig. 35-^, j, 4, 5). Length, 12 to 15 mm., width 5 to 6 mm., 

 height 3 to 4 mm.; testaceous brown; flattened, sub-cylindrical, blunt 

 at the posterior end, tapering and obtusely pointed in front when ex- 

 tended (Fig. 35-^). The head segments usually much retracted giving 

 to the anterior end a bluntly rounded appearance. Each of the body 

 segments, except the first two and 1 the last, with several transverse folds 

 of the integument and a transverse row of twelve segmental bristles 

 each about .15 mm. long. The median and dorsal ones crown the sum- 

 mits of conspicuous, conical elevations which, like the rest of the 

 dorsum, are close-set with short, radiating, black, integumental bristles 

 about .065 mm. long. The transverse body wrinkles are continued 

 laterally into distinct V-shaped prominences bearing the dorso-lateral 

 segmentail bristles and forming a zig-zag longitudinal carina along each 

 side of the body. The lateral segmental bristle is situated at the apex 

 of a similar cone or V underlying the dorso-lateral ; and in front of it 

 a small ventrally-directed fold bears the two ventro-lateral segmental 

 bristles on smaller spiny prominences. The lateral border has thus a 

 very irregular outline of sharp angular projections. 



Mouth-parts with three pairs of small thorns close beside the V-- 

 shaped jaws. The prominent lateral mouth-hooks, found in so many 

 aphidophagous species, wanting. 



In the middle of the third segment is a pair of anterior spiracles. 

 These are light brown, conical, with a semi-circular slit near the apex 

 (Fig. 35-4). 



On the dorsum of the last segment is situated the posterior breathing 

 organ (Fig. 35-^, b; 5). This consists of two closely apposed, short, 

 cylindrical breathing-tubes, united along the middle line, slightly diver- 

 gent at the tip. They are hard, black, firmly chitinized structures, each 

 with three slit-like spiracles raised on radiating carinae. Dorsad near 

 the middle line each is marked by a smooth circular plate about .09 mm. 

 in diameter, their inner margins about .175 mm. distant from each 

 other. The surface of the stigrnal plates between the spiracles is very 

 much roughened the inter-spiracular ornamentation consisting of thin 

 laminate ridges, about as high as the carinae, on which the spiracles are 

 located; only the summits of these ridges are indicated in figure 35-5; 

 about two such ridges on each interspiracular space and continued down 

 the sides of the short tube. The median spiracle at least .25 mm. in 

 length and slender. 



The integument of these larvae is exceedingly tough but transparent. 

 The entire dorsal and lateral surfaces are beset with numerous, minute, 

 short black bristles. The ventrum is bare. Along the mid-dorsal line 

 for the greater part of its length the dorsal blood-vessel is visible 

 through the body-wall. It is a poorly-defined, dark line with five or 

 six lateral expansions. 



As the larva approaches metamorphosis the anterior segments are 

 retracted, the skin becomes inflated filling out the wrinkles character- 



