BURGLARS 283 



grub to full growth, deposits a single gad-fly with 

 her egg. This necessitates her return after a few 

 days with fresh supplies, and a relation of the 

 Ruby Wasp, named Parnopes came a ^ having learned 

 all about the habits of Bembex, waits for this re- 

 opening of the nest and slips in to deposit an egg 

 of her own. The Parnopes grub feeds on the 

 Bembex grub, and the mother Bembex continues 

 to bring freshly killed flies at the proper intervals 

 and never appears to suspect that she is nourishing 

 the murderer of her own offspring. 



The experiences of the Mason Wasp are paralleled 

 by those of the Mason Bee (Chalicodoma muraria). 

 This bee, as we have seen (page 67) constructs its 

 cells of hard cement, in a cluster, and fills up the 

 spaces between and evens up the exterior by 

 more masonry. About the beginning of August 

 when the Mason Bee's grubs should be ful 1 -grown 

 and about to turn into pupae, a Chalcid (Leucospis 

 gigas), got up with bands of black and yellow to 

 look like a wasp, comes along and makes a careful 

 survey of the mass of masonry. There is absolutely 

 no indication from without where the cells are 

 situated within, and how the Leucospis locates their 

 position is a great mystery but she does it. 



From the end of her hind body there is a long 

 boring apparatus and egg-placer combined. This 

 when not in use is kept in ? groove along the back ; 

 but now that she has satisfied herself as to the 

 position of the bee's cells, its position is reversed, 

 and it is gradually thrust through the strong 



