SPHEGID^E. 169 



consist of two layers, the outer verj r thin, the inner tough, 

 parchment-like. The larvae hybernate and turn to pupae in 

 the spring, appearing in the summer and also in the autumn. 



The larva is cylindrical, with the pleural ridge prominent, 

 and with no traces of feet ; the head, which is small and not 

 prominent, and rather narrow compared with that of Pelopaeus, 

 is bent inwards on the breast so that the mouth reaches to the 

 sternum of the fourth abdominal ring. The posterior half of 

 each ring is much thickened, giving a crenulated outline to the 

 tergum. The abdominal tip is obtuse. 



Sphex Lanierii Guerin, according to Smith (Proceedings 

 of the Entomological Society of London, Feb. 7, 1859), con- 

 structs its nest of a cottony substance, filling a tunnel formed 

 by a large curved leaf. The species of the genus are sup- 

 posed to burrow in the ground, and the two cases above 

 cited show an interesting divergence from this habit. Mr. 

 Smith adds, that in "the Sphex which constructs the nest in 

 the rolled leaf, the anterior tarsi are found to be very slightly 

 ciliated, and the tibiae almost destitute of spines, thus affording 

 another instance proving that difference of structure is indica- 

 tive of difference of habit." 



The genus Pelopceus is of a slighter form than in Sphex, the 

 body being longer and slenderer ; the clypeus is as broad as 

 long, triangular above, in front convex, or produced and end- 

 ing in two teeth. The outer costal cell is lanceolate oval, the 

 second subcostal cell subtrapezoidal, being widest above ; it is 

 also somewhat longer than broad. The first median cell is very 

 long and narrow, much more so than usual. The pedicel of 

 the abdomen is long, the first joint in the male being often as 

 long as the remainder of the abdomen. 



The larva of P. cveruleus Linn, is much like that of Sphex, 

 having a cylindrical body with the rings thickened posteriorly. 

 It differs from that of Pompilus in its longer and narrower head, 

 the short broadly trapezoidal clypeus, and the distinctly marked 

 exserted labrum. The mandibles are long and tridentate. 



The pupa (of P. flavipes) differs from that of the Vesparice 

 in having the head more raised from the breast ; the palpi are 

 not partially concealed, as they may be easily seen for their 

 whole length. The long curved mandibles cover the base of the 



