THE SOCIAL INSECTS 



in the New Zealand spring) and found that it was a survival 

 from the previous season. The old queen was alive, but was 

 no longer capable of laying eggs, and this function had been 

 taken over by about twenty of the workers. The next also 

 contained more than forty young queens, of which about half 

 had been fertilised, and twenty-one males. In none of the 

 young queens was there any ovarial development, so that 

 they were really only hibernating in the nest. None of them 

 had taken over the functions of the old queen as in Plath's 

 observation. It is an explanation of facts of this sort in terms 

 of physiology which we most need to advance our know- 

 ledge of social behaviour. For two of the most important 

 differences between solitary and social species are that first, 

 in the latter, young females stay by their mother, and second, 

 that the development of the ovaries is subject to more 

 elaborate control. 



THE STINGLESS BEE 



A bee without a sting seems almost a contradiction in 

 terms, but in one large group of social bees, the Meliponidae, 

 the sting is reduced to a vestige and is useless for defence or 

 attack. The insects are, however, by no means helpless, since 

 they can bite and can smear their enemies with sticky sub- 

 stances, so that populous colonies are as much feared as 

 those of wasps. Stingless bees are found only in the tropics 

 and sub-tropics; they are most abundant in South and Central 

 America, but occur also in Africa, Asia, in some of the Pacific 

 islands and in Australia. The species are very numerous : 

 about two hundred are clearly recognised, while recent work 

 in Brazil suggests that there may be many more. The sting- 

 less bees fall into two groups. Melipona itself is confined 

 to South America and its species are rather large, often little 

 smaller than the honey bee. Trigona, which is found in the 



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