158 



Journal New York Entomological Society. [Voi. iv. 



inner ones are enveloped by the outer pair, which are united into one 

 piece in Polistes ; above, a small inner pair lies between, slenderer than 

 those beneath. The edges of the abdominal segments are a little more 

 thickened than usual, and slightly spinulose; on the side is a promi- 

 nent long slender tubercle. 



Fig. I. Larva and pupa of Pelopceus cenieutarius. ( Trouvelot del.) 



Sphex tibialis St. Farg. 



Larva. — The body of the living larva is somewhat flask-shaped, 

 slightly flattened, gradually widening from the head towards the pos- 

 terior fifth of the body. The head is small and not prominent. There 

 are 13 segments behind the head ; the pleural or lateral ridges are rather 

 prominent, those of each segment well defined, the posterior half of 

 each segment much thickened, giving a crenulate outline to the tergum; 

 the last segment is full, orbicular, the end of the abdomen being full. 



O^ 



Fig. 2. Larva oi Sphex tibialis ; a, side view of head, enlarged. (Trouvelot del.) 



Stigmus fraternus Say. 



Larva. — Body moderately long, slender, cylindrical, tapering 

 slowly towards both extremities; the segments short, very convex, sub- 



