286 PARASITIC BEES. 



the genus Nomada, gaily-coloured insects, with the 

 abdomen smooth and shining. These Bees are for 

 the most part parasitic on the Andrence and their 

 allies. The species of the genus Cceliowys, distin- 

 guished by the conical pointed form of their abdo- 

 men, infest the nests of long-tongued Bees, princi- 

 pally those of the genus Megachile Two species of 

 this genus are found plentifully near London. 



Besides these parasites, which form a little group 

 by themselves, the large hairy Humble-Bees have a 

 peculiar set of idle inmates in their nests; these 

 belong to a genus closely allied to Bombus, and which 

 must therefore be placed amongst the social Bees, 

 although the species exhibit only two forms of indi- 

 viduals, males and females. The latter are distin- 

 guished from the females of the true Humble-Bees 

 by the absence of that peculiar structure of the 

 posterior legs, which, in the Bombi, renders these 

 parts most efficient baskets for the conveyance of 

 pollen. In other respects, these Bees, which form 

 the genus Apathus, exactly resemble the true Bombi, 

 although their colours are often very different from 

 those of the Bees in whose nests they are parasitic. 

 Mr. Smith thinks that these Bees, although seem- 

 ingly idle, must perform some important office in the 

 community which they inhabit, although it is diffi- 

 cult to imagine what this can be, as they do not 

 constantly occur in the nests of Humble-Bees. 

 When there, " they live on the most friendly terms 

 with the industrious part of the community;" but 

 the true object of their presence, like many other 

 things in the natural history of Bees, still remains 

 to be discovered. 



