THE ANTS OR PISMIRES 



its shelters from varied pieces of debris which it spins together 

 with the silk obtained from its own grubs. These shelters 

 may be only an inch or two long or as long as a foot or more. 

 They surround part of the stem or a few twigs from which the 

 food-supplying insects suck the juice. This particular ant 

 often keeps leaf-hoppers of the family known as Membracids, 

 sheltering the adults and the early stages, both of which but 

 especially the young ones supply sweet excreta. Hingston 

 describes ants poking with their heads at a Membracid to 

 make it walk along a branch until it entered the shelter. He 

 also saw ants driving them back into the shelter when they 

 escaped through a hole torn in it by the wind. They also 

 seemed to prevent them from leaving by the entrances which 

 the ants themselves use. A great many ants behave in a more 

 or less similar way to Polyrhachis, but the exact meaning of 

 their behaviour will be understood only when many experi- 

 ments have been carried out. 



HONEY-POT ANTS' 



One well-known and extraordinary development of this 

 type of behaviour is shown in the honey-pot ants. They all 

 occur in the drier parts of the world such as the southern 

 U.S.A., Australia and South Africa. Here there is probably 

 a need to store a reserve of food to tide over periods of 

 scarcity, just as the honey-storing wasps, Brachygastra, do in 

 Mexico. The best-studied species is the one which occurs 

 in Colorado: this ant stores in the bodies of certain workers 

 the sugary liquid which it obtains from aphides, scale-insects 

 and from the surface of an oak-gall. These living storage- 

 tanks are known as " repletes " and have their abdomens so 

 greatly swollen that the hard plates which normally form a 

 continuous armour are widely separated by the distended 

 membrane connecting them. The repletes hang from the 



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