Mar., 1912.] 
Life-Histories of Syrphidae III. 
479 
surface wrinkled, sides irregular. Segmental spines on second 
thoracic (4th) to penultimate (11th) segments, inclusive, and the 
dorso-lateral ones on the prothoracic (3rd) very long, slender, 
black, giving 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. 46). Eracifonn, 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. 46, 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 6 to 1 1 and a 
narrow line along each side of the larva in the dorsal lateral 
carinae. 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 carinae. 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 which is visible through the thin and transparent, though 
tough, body wall. It begins in the head segments where there is 
