142 THE HUMBLE-BEE vil 
By controlling breeding in the case of B. dapr- 
darius, the yellow-banded variety of this species, 
now so rare, could be easily established as a domestic 
breed, and the yellow band broadened and bright- 
ened. Also the British race could be crossed with 
the more prolific races found in Europe, with the 
expectation that a breed would be obtained that 
would produce a much larger number of workers, 
a similar crossing having had this effect in the case 
of the honey-bee. Possibly with controlled breeding 
closely-allied species could be bred together and 
interesting hybrids obtained. 
