THE WAR ON INSECTS 307 



tice is not yet finally settled, and an extensive series 

 of experiments is in progress to determine the most 

 effective methods. Under these circumstances no 

 more is needed here than a reference to the matter, 

 emphasizing its extent and importance. 



By no means all the materials used in the fight against 

 insects have been enumerated here; a few, like gasoline 

 and Delphinium are of very limited application and 

 have been referred to in other connections. But enough 

 has been said to show the chief weapons in our battle 

 with the tiny foes that influence us so much more than 

 is generally known. What is not told is the number 

 of materials and combinations that have been tried 

 and rejected, before those here enumerated were fully 

 tested out and approved. In the reports and bulletins 

 of agricultural departments and experiment stations, 

 almost every year brings records of trials made of new 

 combinations; some originated by the experimenters, 

 some produced by inventors or manufacturers who 

 believed they had discovered something better than 

 was ever known before. Out of all these experiments 

 very little is annually added to our battery; but 

 the limitations of the older materials are becoming 

 ever better understood and the number of effective 

 combinations is larger now than ever before. 



And so in the machinery for applying insecticides 

 and fungicides there is an enormous and continuing 

 progress. A collection of dusters and sprayers dating 

 only ten years back now seems antiquated and ineffec- 

 tive, and as our methods of application become perfected, 

 the benefits derivable increase. 



From the practical standpoint man now carries on 

 his war against insects absolutely without regard to 

 the natural checks of that insect, if it be a native. If 

 it be an introduced species his attempt is to restore the 



