THE CUCKOO BEES 17 



appearance that it is more necessary to search 

 for points of difference than of similarity. There 

 is only one case known of a cuckoo wasp, and that 

 resembles its host even more closely than do the 

 cuckoos of the humble bees. All these points 

 certainly suggest the probability that the social 

 bees and wasps and their cuckoos adopted different 

 habits at a much more recent date than the 

 solitary species, and therefore have not had so 

 much time to become differentiated in structure. 

 The only short-tongued bees which have cuckoos 

 of similar structure are the species of Halictus 

 (pi. B, 12) ; their cuckoos, Spkecodes (pi. B, 11), 

 are closely allied to them, but then Halictus and 

 Sphecodes are most peculiar genera ; although 

 short-tongued, their females spend the winter 

 in the earth, as do the social bees and wasps 

 (see p. 13), and they colonize largely, which 

 may prove to be a step towards socialism. 



B.W.A. 



