CHAPTER XV 



Economic biology. Dependence of man upon nature. Ig- 

 norance of nature the cause of economic loss. Conservation 

 and increase of natural resources. 



An ardent French entomologist in Medford, Mass., was 

 one day eagerly inspecting some caterpillars which he had 

 reared from eggs brought by him from Europe, when some 

 of them, growing tired of his society, made their escape 

 and went on their way rejoicing. This was in 1869. From 

 1890 to 1900 Massachusetts spent about $1,000,000 to fight 

 the gypsy moth. At this time the pest being partly under 

 control the efforts were relaxed, with the inevitable increasje 

 of the pest, and its further spread over a large part of New 

 England and into Canada. At the present time large sums 

 are spent annually by national, state and local agencies for 

 its repression, but in spite of these efforts large areas of for- 

 est are denuded every year and the pest is still spreading. 



In 1850 caterpillars were devouring the trees of the eastern 

 United States. But in England there was a merry, if not 

 melodious little sparrow, who was supposed to enjoy nothing 

 so much as a meal of luscious juicy caterpillars, and so what 

 was more natural than to bring sparrows from the old world 

 to enjoy the rich feasts of caterpillars provided by the new? 

 But no sooner was the immigrant comfortably established 

 in his new home than he proceeded to follow the injunction 

 which the Creator gave to primitive man ''Be fruitful and 

 multiply and replenish the earth," and today he has spread 

 over virtually all of the United States and much of Canada, 

 and is emulating the example of his fellow countrymen by 

 driving before him many of the native inhabitants and in- 

 heriting their patrimony ; so that today the English sparrow 

 is one of the few recognized pests among our birds. 



Inhabiting the wheat fields of the greater part of the 

 United States is a little fly known as the Hessian fly, about 

 an^eighth of an inch long, which lays its eggs on the leaves 

 oif*the wheat, and whose larvae as they hatch crawl down 

 the leaves to their base, where they burrow into the stem 

 and kill the plant. This fly is supposed to have come to 

 America as an unintentional ally of King George with his 



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