CHAPTER V 

 LOSSES CAUSED BY INSECTS : NATURE'S CONTROL METHODS 



To asctu'tain how much man loses by the attacks of injurious insects 

 is a difficult task. The destruction, either partial or entire, of his crops 

 both growing and in storage; of household goods and of food; of our 

 forests and of the wood cut therefrom; injuries to our domestic animals 

 and their products: these and other injuries can be more or less accurately 

 estimated. But when we consider the attacks upon man by disease- 

 carrying insects, resulting in loss of time from productive labor, or even 

 by death, and the actual costs connected with illness, the problem 

 becomes extremely complicated, and to determine how much financial 

 loss this country suffers from insects is a matter for the economist as 

 much as the entomologist. 



Much of this loss ws fail to appreciate, never having had a season 

 free from the attacks of insects which might serve as a standard for 

 comparison. If we could once have such a year entirely insect free, 

 however, the difference would at once force itself upon our notice. 



Crop Losses. — Careful studies of the crops injured by insects have 

 now extended over quite a term of years, and the general conclusion 

 rsached is that in an average year with no unusual attack, a crop will 

 generally produce only about nine-tenths as much as would probably 

 have been the case had insects not been present. When an outbreak 

 occurs, this will decrease production below that point, and instances 

 are far too frequ.mt where for a single crop of some kind, production has 

 been only 20 or 30 per cent of the normal, and many cases are on record 

 where in some localities the destruction has baen complete. 



This estimate covers field crops; destruction of forests and forest 

 products; attacks on domestic animals and their products; articles in 

 storage; on shade trees, shrubs and ornamental plants; on farm wood 

 lots which are not included with the forests; on household goods and foods. 

 With fruit and truck crops the destruction and injury is believed to be 

 more than one-tenth generally. 



Health Losses. — A number of serious diseases of man are due to 

 insects which serve as carriers of the disease-producing organisms. 

 Among these are malaria, the typhoid, typhus and yellow fevers, and the 

 bubonic plague, besides others of less importance. Illness with any 

 of these diseases means that the patient is not only unable to work but 

 is an actual cause of outlay for nursing, treatment, and possibly death 

 expenses also. With hundreds of thousands of illnesses from these 



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