Entomology and Other Sciences 289 



who was then 78 years old and whose sons were all big merchants and 

 prominent citizens of New York. Dr. Howard reported a very pleasant 

 visit with his grandmother and after he left she is reported to have said, 

 "Leland is a good boy, but I do wish he was not in such a trifling busi- 

 ness". 



I wish to discuss principally the importance of insects, the develop- 

 ments in insect control and the relation of entomology to other sciences. 



We have already pointed out that insects cause enormous losses. 

 The most recent estimates place the annual losses caused by insects in 

 the United States at $2,000,000,000, an amount equal to $20 for every 

 man, woman and child in the States. If we prorate this loss to the 

 farmers and others on whom the burden largely rests the cost per farm 

 or farmer per year would of course be many times this amount. In- 

 sects play a part in every phase of life. The direct damage to growing 

 crops is everywhere evident and conspicuous. But we have also the host 

 of insects which attack stored products, those which affect animals, the 

 various annoying pests, and by no means least, those which carry dis- 

 eases of various kinds — the sucking insects which carry mosaic and 

 other plant diseases, the ticks and lice, which transmit disease among 

 domestic animals, and the various insects which are responsible for the 

 transmission of numerous diseases of man. 



In the past fifty years there has been a marked increase in the 

 numbers of insect pests and at the present time there appears to be 

 no lessening of this gradual increase. A common question is, why are 

 insects more abundant than formerly? This is explained in several 

 ways: We may assume that before civilization there was among ani- 

 mals and plants a natural balance which swayed back and forth but 

 which usually balanced fairly evenly. Civilization has brought about 

 unnatural conditions which have interfered with the natural balance 

 and it has been necessary to utilize artificial measures to restore the 

 balance. This interference is due to a number of causes, principal of 

 which are: 



1. Extensive and continuous cultivation of the same or related 

 crops, is favorable to insect reproduction by offering unlimited food 

 supplies continuously year after year; for example, the corn root aphis 

 and corn root worm become most severe when corn follows corn, or 

 the various clover pests which attack only legumes and v/hich appear 

 to be increasing in importance. 



2. Transfer from native to cultivated hosts, which may have been 

 due to the eradication or reduced supply of the native host or to a 

 greater preference for the cultivated and usually more succulent host. 

 Thus, we have the chinch bug attacking cultivated plants of the grass 

 family, the Colorado potato beetle whose native host was the wild 

 Solanum, the curculio which existed only on wild fruits before culti- 

 vated varieties were introduced, and one of recent importance to roses 

 in greenhouses, the rose root worm, which at one time attacked only 

 wild species of Rosaceae. 



3. Transportation has had much to do with the economic entomol- 

 ogy of the United States. More than half of our most destructive 



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