56 HYMENOPTERA CHAP. 



colony may thus still be continued ; but in the latter case, 

 there being no profitable occupation for the bees to follow, 

 they spend the greater part of the time sitting at home in the 

 nest. 



Supposing all to go well with the colony it increases very 

 greatly, but its prosperity is checked in the autumn ; at this 

 period large numbers of males are produced as well as new 

 queens, and thereafter the colony comes to an end, only a few 

 fertilised females surviving the winter, each one to commence for 

 herself a new colony in the ensuing spring. 



The interior of the nest of a bumble-bee (Boinbus) frequently 

 presents a very irregular appearance ; this is largely owing to the 

 fact that these bees do not use the cells as cradles twice, but form 

 others as they may be required, on the old remains. The cells, 

 moreover, are of different sizes, those that produce workers being 

 the smallest, those that cradle females being the largest, while 

 those in which males are reared are intermediate in size. 

 Although the old cells are not used a second time for rearing 

 brood they are nevertheless frequently adapted to the purposes 

 of receptacles for pollen and for honey, and for these objects they 

 may be increased in size and altered in form. 



It may be gathered from various records that the period 

 required to complete the development of the individual Bombus 

 about midsummer is four weeks from the deposition of the egg 

 to the emergence of the perfect Insect, but exact details and 

 information as to whether this period varies with the sex of the 

 Insect developed are not to be found. The records do not 

 afford any reason for supposing that such distinction will be 

 found to exist : the size of the cells appears the only correlation, 

 suggested by the facts yet known, between the sex of the in- 

 dividual and the circumstances of development. 



The colonies of Bombus vary greatly in prosperity, if W 7 e take 

 as the test of this the number of individuals produced in a 

 colony. They never, however, attain anything at all approach- 

 ing to the vast number of individuals that compose a large colony 

 of wasps, or that exist in the crowded societies of the more 

 perfectly social bees. A populous colony of a subterranean 

 Bombus may attain the number of oOO or 400 individuals. 

 Those that dwell on the surface are as a rule much less populous, 

 as they are less protected, so that changes of weather are more 



