SYRPHIDAE OF MAINS. 233 



(Fig. 31-77) consist of three pairs of booklets in addition to the pair 

 of jaws. One pair of booklets is short and heavy, triangular, lateral in 

 position (Fig. 31-77 d) , the other two pairs, situated close beside the 

 jaws (c), are slender, elongate, slightly curved. The jaws (b) are of 

 the usual type but U-shaped rather than V-shaped, the shoulders rather 

 prominent, with a median, terminal, pointed projection. 



The antennae (Fig. 31-77, u), and anterior spiracles are rather well 

 elevated. The latter on a fleshy base with a prominent constriction 

 beyond the middle showing at the apex a small number of rounded teeth 

 or lobes about three larger and three smaller ones, (Figs. 31-74, 75). 



The shape, color and general appearance is very similar to 

 ,the larva of Allograpta obliqua. 



The two .species can, however, be very certainly and definitely sepa- 

 rated on the basis of the posterior respiratory appendages. These are 

 about the same length and other dimensions ; the difference lies in the 

 distal end. As described in Allograpta obliqua the two tubes are 

 slightly divergent at the .tip making them broader here than at mid- 

 length, and bear between each two spiracles a short, but readily visible, 

 spur-like elevation continued as a slight ridge down the side of the 

 tube. In Sphaerophoria cylindrica the end of the tube is very nicely 

 and evenly rounded off ; the spiracles very slightly elevated ; the two 

 tubes slightly emarginate but not at all divergent, and all trace of 

 inter-spiracular spines or projections lacking. The posterior respiratory 

 appendage .35 to .415 mm. long, .31 to .335 mm. wide, .15 to .175 mm. 

 high. The median spiracle about .065 mm. long. The circular plates 

 .035 to .04 mm. in diameter, their inner margins about .065 mm. apart. 

 With the aid of a good hand-lens one can always separate these two 

 species at a glance when the characters have once been fixed in mind. 

 (See Figs. 31-75 and 73 and compare Fig. 31-66 and 68). 



Larvae were taken almost continuously from mid-June to 

 mid-August and probably occurred before and after these dates. 

 The duration in the larval stage appears to be about two weeks. 



Puparium (Fig. 31-75). Length, exclusive of respiratory process, 

 about 5.3 mm., height about 2 mm., width about 2 mm. In general 

 shape, color and appearance so similar to A. obliqua as scarcely to per- 

 mit of separate description. The puparium is generally less strongly 

 elevated on the posterior part. The characters of the posterior respira- 

 tory appendage, however, remain as in the larva and will always serve 

 to distinguish these two species. 



Puparia were taken from June 30 to August 7. In all cases these were 

 found glued by the posterior part of the venter to the leaves of the 

 host plant. The duration in the pupa stage ranged from 5 to 9 days. 



Adult (Fig. 31-71). The following description adopted from Willis- 

 ton (62, p. 105) applies to the adults reared from the above described 

 larvae and pupae. Length 6 to 8 mm. <$. Face and front light yellow, 

 shining; tubercle somewhat fuscous. Antennae reddish yellow. Dorsum 



