Mar., 1912.] Life-Histories of Syrphidae III. 479 



surface wrinkled, sides irregular. Segmental spines on second 

 thoracic (Ith) to penultimate (Uth) segments, inclusive, and the 

 dorso-lateral ones on the prothoracic (ord) very long, slender, 

 black, gi\'ing the young larva a very hairy appearance, so far as 

 I know characteristic of this species. The posterior breathing 

 appendages are short, slightly divergent (Fig. 45, a). General 

 body surface bare. The dorsal blood-vessel shows faintly in the 

 posterior half of the body. 



During subsequent growth these slender segmental hairs are 

 replaced by shorter, stouter, more spine-like bristles ; the posterior 

 breathing appendages are slightly elevated becoming united on 

 the median line; and minute black spines appear all over the 

 dorsal surface of the body. 



Mature larva: Length 11 mm., width 2.5 mm., height 2 mm. 

 (Fig. -16). Eruciform, legless. The segments are not all definitely 

 marked. On the basis of the segmental spines ten segments can 

 be clearly made out posterior to, and including, the one bearing the 

 anterior spiracles (Fig. 40, b). These spiracles may be considered 

 prothoracic, hence we have ten segments exclusive of the head. 

 The head segments are small retractile somewhat indefinite with 

 some appearance of being two in number. For convenience of 

 reference, therefore, the total number has been considered as 12, 

 making the prothoracic, number 3. 



Compared with many other aphidaphagous larvae those of this 

 species are noticably slenderer, in outline with more nearly parallel 

 sides. Segments 6 to 11 are of nearly equal width; the last one is 

 narrower and much depressed; while anterior to segment 6 the 

 body tapers evenly to the mouth-parts when extended, or rounds 

 off at segment 4 when at rest, with the head segments retracted. 



The body wall is prominently wrinkled, transversely, and with 

 the usual two longitudinal carinae at each side. From above as in 

 Figure 46, the ventral of these carinae is hidden by the dorsal one. 



General color yellowish, or salmon-brown, marked with black 

 and white or yellowish white. The whitish markings consist of 

 a transverse rectangular bar on each segment from to 11 and a 

 narrow line along each side of the larva in the dorsal lateral 

 carinfe. Interrupted by the transverse white bars in the median 

 line is the heart line or dorsal blood-vessel, consisting of six, 

 elongate, wedge-shaped black marks broadly margined with brown. 

 Laterad of the brown are other prominent black blotches extending 

 obliquely outward and back to the whitish lateral carinte. The 

 anterior end for two or three segments is unmarked with the black 

 or brown and is light greenish yellow in color. 



Examined more in detail the color markings may be described 

 as follows : The brown color is resident in bodies of globular fatty 

 material w^hich is visible through the thin and transparent, though 

 tough, body wall. It begins in the head segments where there is 



