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FOREWORD. 



The present paper is divided into three parts for the convenience of 

 three classes of readers : 



PART ONE, for those who would apply the results of this investi- 

 gation directly to the prediction of the time of appearance of the codling 

 moth in its several stages in Illinois and in other places where weather 

 conditions are similar, in order to set dates for spraying. 



PART TWO. for those who would check the constants, climato- 

 logical methods, and conclusions regarding the codling moth with data 

 obtained in unusual years or in other climates. 



PART THREE, for those who would utilize the methods here 

 described in the investigation of the same or other organisms. 



