236 MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



The color in this stage changes very decidedly during the develop- 

 ment of the nymph within the translucent puparium. The color being 

 due almost entirely to the inclosed matter is consequently at first the 

 color of the larva — light pea-green with a brownish remnant of the 

 dorsal blood vessel and, at the sides of this, the two whitish lines. The 

 flattened posterior end of the puparium, including the breathing tubes, 

 however, is light testaceous brown, the tips about the spiracles black. 

 Midway on the length of the breathing appendages is a dark brown 

 ring. 



As the pupa develops within, the color changes, gradually losing all 

 trace of the green and assuming more and more the colors of the adult. 

 The first thing to be noticed is the reddish brown color of the eyes 

 replacing the green in the anterior third of the pupa. Later the black 

 and yellow abdominal markings become apparent. 



The puparium is smooth, bare ; the segmental spines inconspicuous. 

 The breathing tubes as in the larva, prominent sub -cylindrical. The 

 wrinkles of the skin often remain rather prominent. 



Adult. (Fig. 31-64). Description after Williston (62, p. 96). "<?. $. 

 Length, 6 to 7 mm. Face yellow, often with a bluish reflection, slightly 

 brownish on the tubercle. Frontal triangle yellow ; front in the female 

 shining black on the vertex, continued as a broad stripe (broadest 

 below) to the antennas; on the sides the yellow of the face continues 

 up along the eyes nearly to the ocelli. Antenna? reddish-brown, black- 

 ish on the upper part of the third joint. Thorax deep shining green, on 

 the sides with a yellow stripe reaching from the humeri to the suture, 

 where it is sharply truncate ; post-alar callosity also yellow. Scutellum 

 wholly light yellow, faintly reddish on the disk; pile black. Abdomen 

 black or brown ; first segment, except a slender transverse spot on each 

 side behind, yellow; second segment with a slender yellow anterior 

 fascia, and a broader one in the middle, about a third of the width of 

 the segment ; straight and but slightly widened at the sides ; third seg- 

 ment with a broad arcuate band, not quite touching the posterior angles 

 on the sides ; fourth segment with two slender parallel stripes, leaving 

 a slender black stripe between them, on each side a broader, oblique, 

 oval spot, touching, or narrowly separated from the anterior end of 

 the yellow longitudinal stripe, and reaching to the posterior angles ; fifth 

 segment similar, but the side spots less oblique. Legs light yellow ; last 

 three joints of all the tarsi, the hind tibiae, except the base and a middle 

 ring, and a ring on outer part of hind femora, brownish. Wings hyaline, 

 veins black." 



Syrphus americanus Wiedemann. 



(See also 32, p. 477 and 35, p. 55.) 

 This American Syrphus-fly apparently ranges throughout 

 North America and ranks along with Sphaerophoria cylindrica 

 as one of our most valuable predaceous forms. The larvae have 



