NATURAL HISTORY OF SOUTH AFRICA 



at a time, and the entire life cycle from egg to grub 

 and chrysalis and the emergence of a full-grown fly 

 is only a fortnight ; therefore every female fly will 

 produce 120 more flies in a little over two weeks from 

 the day she emerges from the chrysalis. If a female 

 fly escapes destruction in the spring, and if allowed to 

 breed unchecked, then the progeny of that single fly will 

 amount to something like 6,488,560,000,000 before 

 the chills of winter appear. The familiar wagtail, 

 which loves to dwell in cities and villages and around 

 homesteads, feeds its young largely on flies, their 

 grubs, and chrysalides, and yet we permit our 

 children to rob its nest or murder it with a cata- 

 pult or air-gun. We rear cats because we are too 

 " tender hearted " and sentimental to painlessly kill 

 them when born. We think we are doing a kind- 

 ness when we give these kittens away. We 

 would pause and reflect if we knew that the great 

 majority of these kittens grew up into hungry, 

 mangy cats, whose chief diet consisted of our allies 

 the birds. 



I have watched the nests of warblers, fly-catchers, 

 weavers, larks, starlings, sun birds, and numbers of 

 others for an hour at a time during varying periods 

 of the day. From these observations it was shown the 

 parents brought insect food to the young about twenty 

 times an hour. Sometimes the number of visits were 

 less, but as often as not they were over twenty. The 

 parent birds often bring two, three, and often more 

 caterpillars at a time ; but, taking one as the average, 

 and twelve working hours, we have a total of 240 



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