PREFACE. 



IN looking back over the past ten or twelve years, it is dif- 

 ficult to realize the rapid advance made in combating the 

 insects and fungi which attack our cultivated plants. It is not 

 going too far to say that the discoveries made within this 

 period have worked almost a revolution in certain lines of 

 agriculture. So phenomenal has been the progress in this 

 direction that we are sometimes led to think that we have gone 

 forward too fast, for in our intense desire to make the work 

 thoroughly practical we have in many cases merely skimmed 

 the surface, overlooking some of the most important funda- 

 mental questions involved. However this may be, the fact 

 remains that America to-day stands well to the front in the 

 discovery and application of practical methods of dealing with 

 the numerous insect and fungous enemies of cultivated plants. 

 The advance in this department has been so rapid that it has 

 hardly been possible for investigators to keep track of all that 

 has been written on the subject, nor has it, under the circum- 

 stances, been an easy matter to pause and consider what is to 

 be the final outcome of work of this kind. This seems to be a 

 fitting time, therefore, to take a broad survey of the subject in 

 order that we may see where we stand. Mr. Lodeman has 

 done this in the present volume, in which is given a clear, con- 

 cise statement of the existing condition of our knowledge on 



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