How Insects Cause or Carry Disease 41 



trees or ponds may be breeding their millions just 

 as these and you will only begin to comprehend the 

 meaning of this statement. 



As long as these myriads of insects keep in what 

 we are pleased to call their proper place we care 

 not for their numbers and think little of them ex- 

 cept as some student points out some wonderful 

 thing about their structure, life-history or adapta- 

 tions. But since the dawn of history we find ac- 

 counts to show that insects have not always kept 

 to their proper sphere but have insisted at various 

 times and in various ways in interfering with man's 

 plans and wishes, and on account of their exces- 

 sive numbers the results have often been most dis- 

 astrous. 



Insects cause an annual loss to the people of the 

 United States of over $1,000,000,000. Grain fields 

 are devastated ; orchards and gardens are destroyed 

 or seriously affected ; forests are made waste places 

 and in scores of other ways these little pests which 

 do not keep in their proper places are exacting this 

 tremendous tax from our people. 



These things have been known and recognized 

 for centuries, and scores of volumes have been 

 written about the insects and their ways and of 

 methods of combating them. 



But it is only in recent years that we have begun 



