l6o MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



we were forced to stop spraying before the end of the season 

 due to the scalding of the leaves, while in other yards and in 

 the orchards it was decided to discontinue the use of soluble 

 poisons and substitute insoluble arsenicals. In visiting the 

 owners during the next season, however, they were so delighted 

 with the crop of sound apples obtained in the previous year, 

 that they promptly forgot all about the alarm created by the 

 partial defoliation, and without exception, permission was 

 granted to spray the apple trees again. Nevertheless, during 

 the second season the fear of some injurious effect of spray 

 injury to the trees was voiced repeatedly. Many people, how- 

 ever, preferred sound fruit even if burned foliage was the 

 necessary price. Raking the leaves from well kept lawns where 

 apple trees were growing proved to be a troublesome task. 



Effectiveness of poisoned bait. An attempt was made to 

 determine how long the poisoned bait would remain effective 

 after different amounts of rainfall. After each treatment, 

 cheese cloth was fastened to the ground with spikes below a 

 sprayed tree. The insects which succumbed to the effects of 

 the soluble poison in the sweet were collected daily from the 

 cheese cloth and it was reasonable to suppose that the insecti- 

 cide became ineffective due to rains when no dead specimens 

 were found. As the records on precipitation at the University 

 of Maine were taken at a distance of about two miles from our 

 experimental area, no accurate statement can be made as to the 

 amount of rainfall required to wash off all the bait. It is evi- 

 dent, however, that an "all day rain" with heavy intermittent 

 showers will destroy the effectiveness of the fruit fly remedy. 

 In view of the abundance of rain in the season of 191 5, the 

 effectiveness of the poisoned diluted molasses was put to a 

 most thorough test. 



An experiment was performed in the field to determine the 

 length of time required for the amount of poison used in the 

 formula in 191 5, to kill the adults. A tall Benoni apple tree 

 (Map, L) received the fourth treatment on August 19, at 3.30 

 P. M. and on August 20, at 7.30 A. M. six female and four 

 male apple fruit flies were collected on the cheese cloth sixteen 

 hours after the application of the bait. Four specimens feed- 

 ing on the insecticide on the upper surface of the leaves were 

 captured, but all died in captivity within two days. On Augu-t 



