How Animals Work. 



during the hot summer months in the crowded slums 

 of our large industrial cities is largely due to infection 

 being carried from house to house, and from room to 

 room, by the house-fly. Now, if you will watch the 

 wasps, leaving them undisturbed, you may see how 

 they will hover about the garden or a room, pouncing 

 upon the flies and carrying them off in triumph, only to 

 return a few moments later in search of more. Indeed, 

 standing one hot summer afternoon in a typical squalid 

 street of one of our towns, looking at the black masses 

 of flies that were swarming over the various articles of 

 food exposed for sale on the slab of an open shop front, 

 my attention was attracted to a constant stream of wasps, 

 going and coming with the greatest regularity, each 

 departing wasp carrying off a captured fly. As on the 

 average one wasp arrived and promptly pounced upon 

 a fly every fifteen seconds, it was a most convincing 

 demonstration of the value of the wasp in helping to 

 destroy the horrible, disease-spreading house-fly. 



But now let us consider the Common Wasp as an 

 architect and builder. The nest is really a very remark- 

 able structure, more or less globular in shape, and 

 generally hidden underground, in some wayside bank 

 or hedgerow. The Queen Wasp is the foundress of 

 the nest, and the whole structure is built up in a com- 

 paratively short space of time, the close of the autumn 

 seeing the death of its teeming inhabitants ; for the 

 wasps do not lay up stores of food arfd continue as 

 a permanent community year after year, like their 

 cousins the hive bees. The first really warm days of 

 spring see the Queen Wasp coining forth from some 

 snug retreat where she has slept through the long, cold, 



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