262 MAINE AGRICULTURAL EXPERIMENT STATION. I9I5- 



very troublesome in the orchards of Cherryfield in 1914 neither 

 there nor elsewhere did the writer observe any flies on the apples 

 that were subnormal in size. These observations are in perfect 

 accord with those made by Professor O'Kane in New Hamp- 

 shire. 



The writer has not succeeded in inducing the fly of the apple 

 maggot to lay eggs in blueberries. This experiment has been 

 tried a number of times both in the laboratory and in the field. 

 A large cage was placed over a healthy blueberry plant, and 

 about 20 adult Rhagoletis just captured on apple introduced, 

 but they refused to oviposit. This was done twice in the field 

 and on a smaller scale several times in the laboratory and insec- 

 tary, always with negative results. At various times during the 

 past summer the writer introduced some 20 or more half-grown 

 blueberry maggots into apples of various kinds, inserting them 

 beneath the skin in such a way that they could burrow into the 

 pulp before drying up, but not a single one developed sufficiently 

 to form a puparium. Likewise flies taken on blueberries refused 

 to oviposit in apples, but as they also showed so much reluctance 

 in the laboratory to oviposit at all one should not lay too much 

 stress on this point. 



At any rate the writer is inclined very strongly to believe that 

 biologically at least there are two distinct strains or races of 

 Rhagoletis pomonella Walsh, the one breeding in the apple and 

 related fruits and the other in smaller fruits such as the blue- 

 berry and huckleberry. There does not seem to the writer to be 

 any other conclusion which will explain the data given above. 

 Certainly in so far as Rhagoletis occurs in Maine the form on 

 the apple and the form on the blueberry are entirely independent. 

 The "oldest inhabitant" of the barrens cannot remember a time 

 when there were not maggots in the blueberries, while the intro- 

 duction and spread of the apple maggot in the state is a matter 

 of record and is discussed by Professor Harvey in the Annual 

 Report of this Experiment Station for 1889 and subsequenf 

 years. In Maine the blueberry maggot apparently did not mi- 

 grate to the apple nor vice versa and the two races have lived 

 on independently side by side. 



The original host plant of this insect is as much a matter of 

 theory as ever. Professor O'Kane has shown that it must have 

 been some species of haw, or else the blueberry or huckleberry 



