ON TWO SPECIES OF SPHEX. 75 



In the inside of houses, nothing furnishes both these species 

 of sphex with a more convenient situation for their cells than 

 the backs of picture frames; for they are fond of building in 

 places which have a very moderate degree of light, and the 

 back of a picture frame hanging against the wall has also the 

 advantage of furnishing two sides of the cell. A hollow 

 moulding of a pannel has also its strong temptations, or the 

 internal angle of the frame of a table. In the wooden houses 

 of Virginia they occupy all these situations in great numbers. 

 I have seen the hollow space in the front of the books in a 

 library occupied by a whole tribe of the sphex coerulea, which 

 thereby saved themselves much trouble, as they had only to 

 close the space between the edges of the binding. 



The sphex Pcnnsylvanica differs exceedingly from the coe- 

 rulea in the construction of his cells. Instead of a series of long 

 tubes divided into separate cells,' the former builds separate- 

 horizontal apartments close to each other. They are perfectly 

 smooth internally, but roughly finished on the dutside. See 

 No. II. Fig. 3 & 4: of both these species of cells the figures 

 give an exact representation, both as to size and form. 



The food provided by both species for their offspring is 

 however exactly the same, namely spiders of every genus and 

 species, chiefly however of those who do not fortify them- 

 selves by extensive webs. There is a common yellow spider 

 which they collect in the greatest numbers. I have however 

 observed both the Pennsylvania and coerulea attack large 

 spiders, in the midst of their webs and of the dead bodies of 

 other insects which had fallen victims to them; especially in a 

 remarkable instance: the sphex flew nimbly at the spider and 

 stung him. He then retired to clean himself from the cobwebs. 

 This he did in the manner of a fly, using his hind legs to wipe 

 his wings, and his fore legs to his head. After several attacks 

 the spider at last attempted to escape by letting himself down 

 to the floor, by a thread. He then ran away, but his enemy 

 followed him, and frequently stinging him attempted to carry 

 him off: but the spider was too large and heavy; and though 

 the sphex endeavoured to lighten his load by biting off the 

 spider's legs, he could not succeed while I observed him, which 

 was for at least half an hour. 



