THE APPLE MAGGOT. 



W. C. O'Kane. 



(A list of references will be found at the end of this bulletin. 

 The numbers in parentheses in the text refer to these cita- 

 tions.) 



INTRODUCTION. 



The Apple Maggot, or railroad worm, Rhagoletis pomonella 

 Walsh, is clearly one of the principal insect enemies of the apple 

 in the northeastern fruit-growing region of America. Through 

 much of this area orchardists are familiar with the brown tun- 

 nels made by the larvae through the pulp of the fruit, especially 

 in early varieties, and with the small white maggots responsible 

 for the damage. Commonly the grower describes the situation 

 with the statement that he cannot raise any early or sweet fruit 

 that is fit to eat. Often the comment is added that sometimes 

 his winter fruit is invaded, especially trees in certain locations 

 with reference to the rest of the orchard. 



An investigation of the species was begun by the New Hamp- 

 shire Agricultural Experiment Station five years ago. The work 

 was started with preliminary studies by Professor C. F. Jackson 

 in the summer of 1909. It was made a major project of the 

 Station in the fall of the same year under the direction of the 

 writer, and has remained actively in hand throughout the suc- 

 ceeding four years. 



Certain information secured, of a direct practical bearing, 

 was made public in a circular sent to the New Hampshire mail- 

 ing list in 1911 (41). Some facts of interest to entomologists 

 were published in the Journal of Economic Entomology in the 

 same year (42). The complete record of the investigation to 

 date is presented in this bulletin. 



Grateful acknowledgment is made of the zealous and pains- 

 taking work of the writer's assistants, Mr. C. H. Hadley, Jr., 

 and Miss Cornelia F. Kephart. Most of the field studies of the 

 last two years have been worked out by Mr. Hadley. The 

 investigation has been favored, also, by consistent support on 

 the part of Director J. C. Kendall, of this Station. 



