VARIETIES OF WASP SOCIETY 



others produce nearly all males. The second sort of colony 

 is one in which the queen has died early. 



At the end of the season many of the grubs in the Polistes 

 colony die and may be thrown away by the workers. This 

 seems to be much the same as the autumnal destruction of 

 grubs by the common wasp, though in Polistes they are not 

 killed by the workers. Deleurance has obtained good evi- 

 dence that the production of "aborting brood" is due to some 

 lack in the food provided by the workers, probably in some 

 glandular secretion which they are no longer able to supply. 

 By rearing his wasps in captivity at a constant temperature, 

 he was able to have colonies at all stages of development 

 simultaneously. He could then show that brood from young 

 nests aborted if given to old wasps and, conversely, brood 

 from old nests could complete its development successfully 

 if the old workers were replaced by young ones. Since, 

 however, in both experiments the wasps were given plenty 

 of insect food, abortion cannot be due to simple scarcity. 

 It is probably due to the exhaustion of one of the glands 

 whose secretion is mixed with the food. This idea is supported 

 by an experiment in which the workers were kept cool (4 C) 

 at night, so that they did not age so rapidly. With this 

 treatment, brood could be reared normally in the laboratory 

 for seventy days instead of the usual maximum of thirty-five 

 days. 



The species Polistes gallicus is particularly interesting 

 because its habits have been studied over a wide range of 

 climates, extending from north Germany to the oases of the 

 Sahara. In the north, colonies are usually founded in the 

 ordinary way by a single queen after hibernation. In south 

 Germany, more than one queen is often seen on a nest. 

 Heldmann noticed that several queens might begin to build 

 nests on one beam of a shed. When none had more than 



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