ii FOOD OF INSECTS 49 



growing inability for the more onerous and arduous 

 labours of building and of gathering and carrying home 

 honey. The larvae of wasps are somewhat more 

 hardy than those of bees, their head is larger and of 

 greater strength, and the mouth is stouter. They 

 therefore receive occasional bits of fruit and fragments 

 of insects in addition to the usual fluid, or very soft 

 nutriment, upon which alone ants and bees are bred. 



The young of solitary bees and wasps are able 

 to take their nourishment unaided if it be placed 

 beside them. But the mothers of certain species 

 cannot make such provision, being deficient in the 

 structures necessary to enable them to build and 

 collect the proper food. They therefore use their 

 wits instead of labouring, and introduce their eggs 

 into a nest that is already victualled by some in- 

 dustrious Hymenoptera for its own progeny. The 

 usurping larvae are hatched sooner than the rightful 

 inheritors of the home, and utilise the nutriment 

 that surrounds them without care for the sorry plight 

 of their defrauded companions. 



Some kinds of ants are similarly helpless. Their 

 difficulty is very great, for ant-larvae must be fed from 

 the mouths of nurses. The method of cutting this 

 gordian knot of perplexity comprises one of the most 

 curious and extraordinary phases of the many-sided 

 ant character ; it is a marvellous imitation of the 

 ways of man. They make regular periodic raids 

 and forays upon the nests of other ants and carry 

 off their workers, training and subjecting them to 

 undertake the offices in which they cannot themselves 

 engage. The adults of the foreign colonies are not 



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