ANNUAL REPORT, 1933 33 



Apple Maggot Control. (A. I. Bourne.) A combination of fav^orable weather 

 conditions, especially during the period of emergence of the flies, which allowed 

 the insect to follow closely its normal course of seasonal development and more 

 accurate timing of the sprays for its control, enabled growers to hold the pest in 

 check very satisfactorily. At the same time there was sufficient evidence from 

 unsprayed blocks to show that this control was not due to any scarcity of the 

 insect over the State as a whole. 



In the 9 orchards where control demonstrations have been conducted and 

 in which the complete control program was continued, only 9 apples out of a 

 total of 7,688 examined were found to be infested, an average of 0.12 per cent 

 infestation; in 5 of the orchards no evidence of maggot injury was discovered; 

 and in only one block did the fruit score less than 90 per cent clean. One grower, 

 whose fruit scored less than 3 per cent clean in 1929, the year preceding the 

 demonstration, largely because of failure to control apple maggot, secured in 

 1933 a crop scoring 93 per cent clean fruit with no evidence of maggot injury. 



The work was extended from a demonstration in individual orchards to an 

 attempt at a community program in so-called maggot control areas where several 

 growers, whose blocks were located in a well-defined area more or less isolated 

 from outside orchards, were united in a campaign to control maggot in that 

 area. The success of such a plan depends upon the thorough cooperation of all 

 the growers. Results showed that successful maggot control was in direct 

 proportion to the extent to which each grower carried out his assignment. 



In one area comprising approximately 15,000 trees in commercial blocks, apple 

 maggot damage of from 5 to 10 per cent on Baldwins was recorded when a com- 

 plete spray program was supplemented by the removal of wild, pasture, or road- 

 side trees in the vicinity of the commercial orchards. Where the environmental 

 factors were ignored, and neglected trees were allowed to remain standing, from 

 60 to 100 per cent of the fruit was found to be infested by maggot, and in nearby 

 commercial blocks the fruit showed from 20 to 50 per cent infestation. Many 

 hawthorn trees were found in this area and much of the fruit was found to contain 

 maggots. 



In a somewhat smaller area where, by the united efforts of the group of growers, 

 all neglected trees were removed and an adequate spray program was carried 

 out in all the commercial blocks, the infestation on Baldwins ranged from to 

 7 per cent, with an average infestation of 1.8 per cent. In all but one case maggot 

 damage was less than 2 per cent and in every case maggot injur}' was much less 

 than that of the previous year. 



Studies on the dispersal of apple maggot flies, supplementing those of Phipps 

 and Dirks in Maine, led to recovery of flies at a distance of from 600 to 700 yards 

 from the point of liberation. The maximum range in previous records of re- 

 covery was approximately 300 yards. This indicates that under favorable condi- 

 tions these insects may fly for longer distances than previously supposed, which 

 may account for severe outbreaks which have hitherto been baffling to explain. 



Introduction of Parasites of Oriental Fruit Moth. (A. I. Bourne.) The 

 introduction of parasites of the Oriental fruit moth was extended to practically 

 every section of the State where peaches are grown on a commercial scale and 

 where the infestation of Oriental fruit moth was severe enough to promise success- 

 ful establishment of the parasites. 



Approximately 60 colonies comprising 15,000 specimens of Macrocentrus 

 ancylivorus were liberated in 8 counties of the State. In addition, liberations 

 were made of several colonies of newly introduced parasites, some of which 



