xviii PREFACE 



damage caused by the Pea Aphis, or any 

 other of the insect pests here described. 

 The writer did not trust to his own knowl- 

 edge of Entomology. Insect specimens in 

 each case were submitted to the Depart- 

 ment of Entomology, United States De- 

 partment of Agriculture for identification, 

 and there due credit belongs. 



This book is primarily intended to be a 

 practical treatise. The aim cannot be at- 

 tained if our study is to be deprived of its 

 scientific basis and its scientific value. It 

 is hoped this double character of the work 

 will make it a means of ready reference 

 for both growers and investigators. 



During the past four years numerous 

 letters of inquiry have been received by 

 the writer from sweet pea growers rela- 

 tive to various difficulties, especially those 

 of a pathological nature. Although hesi- 

 tating to make hasty suggestions, we could 



