[ 73 J 



No. XV. 



On tzco species of Sphex, inhabiting Virginia and Pennsylvania', 

 and probably extending through the United States. By R. 

 Henry Latrobe. 



Read January 21st, 1803'. 



Philadelphia January, 21st, 1803. 



The two species of Sphex to which this memoir is confi- 

 ned," are well known under the names, blue wasp, mason, and 

 dirt-dauber. Among all the remarkable insects belonging to 

 the order of hymenoptera of Linnaeus, they appear to be most 

 distinguished by their singular and cruel mode of providing 

 for their young. 



The two species are distinguished from each other in their 

 manner of building, and in the form of their bodies; but agree 

 exactly in their mode of life, in the materials of which they 

 build their cells, and the food provided by them for their off- 

 spring. 



The first, No. I. Plate I. is probably the Sphex coerulea of 

 Linnaeus, of which die following is the description : 



Coerulea, alis fuscis: habitat in America septentrional!. 



This sphex, is by far the most common of the two species ; 

 the antennae are pointed and stand up when he is at work. 

 His nose is furnished with a strong beak, with which he works 

 sideways, leaving ridges on his cells which make them appear 

 to be plaited; his thorax is thick, the abdomen petiolated. 

 From the scutum attached to the petiole^ is extended a strong 

 hook, which is very serviceable to him in securing his prey. 

 His sting is not very painful, and soon ceases to be troublesome. 

 The wings which Linnasus describes as brown, play between 

 a beautiful green, brown, and blue. The joints of the feet 

 are yellow, the whole of the head, body, and legs are blue,. 



M. 



