34 APPLIED ENTOMOLOGY 



of the product saved, and such measures used with judgment represent 

 one of the cheapest and most successful forms of crop insurance. 



It is certain that the time will never come when protection of crops 

 from insect ravages will ever be so universal and successful that to produce 

 crops will not pay, for with our increasing industrial population to be fed 

 the demand is more likely increasingly to exceed the supply, even though 

 every crop producer should finally come to the protection of what he raises, 

 from insects. At present the farmer who adopts modern methods against 

 insect injuries is certain in any term of years to raise more and to sell at 

 higher prices than one who trusts to chance or "luck" in this phase of his 

 induvstry. 



Figures on Losses. — From the above it becomes evident that no 

 accurate figures as to the losses caused by insects can be given. We can 

 only recognize that everj^thing produced which is destroyed by these pests 

 is thereby lost to the country as a whole, even though some individuals 

 may profit. To value this destruction we have only the prices for which 

 crops sell, as a criterion, and the point has already been brought out that 

 if the tenth destroyed had been saved, the price of the whole might have 

 been no greater than it was for the nine-tenths actually produced. Tak- 

 ing this unreliable standard, however, in order to get some slight idea of 

 the amount of destruction ordinarily caused by insects, we may bring 

 together the following statement, based on the average value of the crops 

 for the five years 1913-1917 as given in reports of the United States 

 Department of Agriculture and from other sources. 



Field crops $833,660,000 



Animals and their products 431 ,450,000 



Forests, forest products and materials in storage 300 , 000 , 000 



Loss by human disease and death 350 , 000 , 000 



Farm wood lots 100,000,000 



Extra losses on fruit and truck crops ? 



Shade trees and ornamental shrubs and plants ? 



Household goods and foods ? 



Altogether, if we may accept figures based on the assumption, as has 

 been indicated, that if no losses had occurred the value of the whole 

 would be at the same rate as the actual price for what was obtained, it is 

 safe to estimate the loss in the United States due to injurious insects as 

 being not far from two billion dollars each year. How nearly correct this 

 is, however, no one can tell, so many factors enter into the problem. 



Causes of Increased Injury. — Losses to crops, forests and other mate- 

 rials are increasing, for several reasons. Before the settlement of this 

 country there were, of course, native insects attacking the various plants 

 growing here. When settlements were established new plants were intro- 

 duced by the settlers and grown in greater abundance than if they were 



