SOLITARY AND SOCIAL BEES 



biting a hole near the bottom of the nectary, so that they can 

 rob it without coming in contact with pollen and fertilising 

 the flower. Once the hole has been made long-tongued 

 species may use it, too, so that much harm may be done. 

 However, for many years New Zealand was able to obtain 

 all the clover seed that was needed, and it is only recently 

 that difficulties have again arisen. It is not clear whether for 

 some reason the long-tongued bee has become less numerous 

 or, as I think is more likely, that the area under clover has 

 been increased without any corresponding increase in the 

 possible nesting-sites. 



The humble bees which live in tropical countries have 

 not been much studied, but it seems that some of them, as 

 in the tropical social wasps, live in colonies with several 

 queens and found new nests by means of a swarm of workers 

 and queens. This has been recorded by von Ihering in 

 Brazil, but further accounts of the habits of humble bees in 

 the equatorial region would be very interesting. Foundation 

 by swarms is probably developed because in that climate 

 hibernation is unnecessary ; hence any surplus workers can 

 accompany the young queens when they leave the colony. 



Observations by Plath in the United States support the 

 idea that colonies might become perennial, the old queen 

 being replaced by a new one when she was worn out. In one 

 American species he observed this to take place in two 

 separate colonies at the end of August. In one of them one 

 large crop of new workers was produced in September and 

 a second crop of males and queens in October. This is 

 exceptional behaviour in a temperate climate, and might be 

 possible only in a favourable year. 



In New Zealand Cumber found that one of the introduced 

 British species behaved on one occasion in a rather different 

 way. He dug up a large nest on November 4 (which is early 



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