SOME OTHER BEES 279 



similar places and come out in the spring to found new 

 colonies. They are fully equipped for the work of nest-building 

 and foraging, though they do not build comb, but, having found 

 a suitable hole and lined it with moss or grass, place a mass of 

 pollen and honey in the centre, deposit some eggs and incubate 

 them. When the larvae are growing, more food is collected by 

 the mother, but when the workers, which this first batch of eggs 

 produces, have come to maturity, the work of foraging is taken 

 up by them and the queen remains within the nest, keeping 

 up the production of eggs. 



Bombus, therefore, forms a very marked half-way house 

 between the solitary bees and the perfectly social species. 

 The habits of all members of the genus are generally similar, 

 though each species varies a little in details. Thus B. terrestris 

 invariably builds in a hole in a dry bank, while B. lapidarius 

 chooses a stone under which it excavates a hollow for its nest. 

 The Carder-bees build their nests of moss on the surface, 

 generally under the protection of a bush. An interesting habit 

 of several species is that of making a back entrance to the 

 nectaries of certain flowers whose tubular corollas are too 

 narrow and deep for them to enter. This habit can be witnessed 

 by anyone who cares to watch Bumble-bees at work in a field of 

 beans. Proceeding to the base of the flower, the insect tears a 

 hole with its jaws and extracts the nectar. I have noticed that 

 honey-bees and ants will often make use of this back entrance, 

 though I have never seen them make it themselves. 



A genus closely allied to Bombus is remarkable for being 

 parasitic on the latter. This genus, Apathus, is structurally but 

 little different, having even the dilated hind tibiae and "tarsi, 

 which are the foundation of the corbicula, or pollen basket, 

 but without the necessary bristles which hold the load in 

 position. They produce no workers, and are, indeed, properly 

 speaking, solitary species, their simple plan being to enter the 

 nests of Bombus and deposit their eggs in the food, leaving the 

 larvae to be reared by the host, 



IV 



The details of cell-making, lining of the nest, collection of 

 honey and pollen and its conveyance by special contrivances, 

 which, in such complexity, make up the circle of labour dis- 

 tributed with exquisite nicety in Apis, are found in their 

 primitive form in one or other of the numerous species of solitary 

 bee, and in very many cases the survival of the species 

 manifestly depends on the high development of one of these 

 details, instead of all-round advancement. 



Thus, the Mason-bees have remarkable facility in the art 



