June, 1912.] Life- Histories of Syrphidae IV. 539 



of poorly defined pro-leg-like projections of the body on the ventral 

 side. The mouth-parts (Fig. 77) consist of three pairs of hooklets 

 in addition to the pair of jaws. One i^air of hooklets is short and 

 heavy, triangular, lateral in position (Fig. 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 antennge (Fig. 77, a) and anterior spiracles are rather well 

 elevated. The latter on a fleshy base with a prominent constric- 

 tion beyond the middle showing at the apex a small number of 

 rounded teeth or lobes about three larger and three smaller ones. 

 (Figs. 74, 75). . ■ . . 



The shape, color and general appearance is very similar to the 

 larva of Allograpta obliqua. vSo much so in fact that I was unable 

 for a long time to distinguish the two and was being constantly 

 bafBed by the issuance of adult Sphcerophoria from my stock of 

 supposedly AUograptid larvae and pupae. There is an indefinable 

 difference in the naked eye appearance as near as I can express it, 

 due to the more finely and evenly granular appearance of the fat 

 bodies visible through the dorsal wall in Sphcerophoria. But I am 

 not sure that this is constant. 



The two species can, however, be very certainly and definitely 

 separated on the basis of the posterior respiratory appendages. 

 These are about the same length and other dimensions; the differ- 

 ence lies in the distal end. As described in Allograpta obliqua the 

 two tubes are slightly divergent at the tip making them l3roader 

 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. Now in Sphcerophoria 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. 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. 72 and 73 and compare 

 Figs. 6Gand6S). 



On June 4th larvee of this species were taken from among 

 Aphis brassiccB in a greenhouse on the University Campus. At 

 Sandusky, larvae were found commonly on curled dock (Rumex 

 crispus) June 20th and later. At Lakeville, larvee w^ere taken 

 from thistle (Cardiius sp.) among Aphis sp. ilugust 27, 1911. In 

 Autumn they are rather common on cabbage, in gardens during 

 September. Aphis brassicce Linn, seems to be their favorite prey, 

 though they are not restricted to this species, and may be found to 

 be rather ubiquitious. 



