84 BEES AND WASPS [OH. 



of various species of "cuckoo" bees belonging to the 

 genus Coelioxys. In structure, as is so frequently 

 the case, these ."cuckoos" closely resemble their hosts, 

 but their superficial appearance is very different. In 

 size they are somewhat smaller ; in colour they are 

 black with conspicuous white bands; while the ab- 

 domen is almost destitute of hairs, and in the females 

 is very finely pointed : the abdomen of the males ends 

 in a series of spines. In the case of solitary bees, like 

 Megachile, which do not form colonies after the fashion 

 of Anthophora, the question inevitably occurs, "How 

 do the * cuckoos' find the nest of the bee that is to 

 foster their young?" A lucky chance enabled me to 

 throw some light on this point. One day towards the 

 end of June, 1906, I happened to see a Coelioxys 

 quadridentata enter the burrow of a Megachile cir- 

 cumcincta. I dug the nest out of the burrow and in 

 so doing scattered the sand over an area of several 

 square inches, completely effacing all trace of a burrow. 

 I awaited the return of the Megachile in order to 

 identify the species, and was astonished in the course 

 of the next ten minutes to see and capture two more 

 specimens of Coelioxys which came up against a fresh 

 breeze that was blowing at the time, and alighted on 

 the disturbed soil. It is evident that these "cuckoos" 

 must have been attracted to the spot by the scent 

 of the excavated nest. I may further mention that 

 Coelioxys was not abundant on that occasion, for 



