soluble; poisons in the poisoned bait spray. 155 



ber of different formulas of the poisoned bait to control the 

 olive fly (Dacus oleae Rossi). In 1911, Illingworth used the 

 following "fly destroyer" as given by Merck to control the 

 adult of the apple maggot in New York : 



Syrup 4 parts or 4 pts. 



Potassium arsenate- ... 1 part or 1 lb. 



Water : . . . 45 parts or 45 pts. 



In 1912, Illingworth used the following formula: 



Molasses 1 lb. or 25 lb. 



Arsenate of lead 3 oz. or 5 lb. 



Water 4 gal. or 100 gal. 



The author states that, "If the conditions are such that the 

 flies do not succumb readily to this treatment, the use of the 

 soluble potassium arsenate is advisable as previously described." 

 To determine the effectiveness of different amounts of vari- 

 ous kinds of soluble poisons used in the bait, and the extent 

 of injury to the leaves and fruit, a number of preliminary ex- 

 periments were performed. With each formula that was useu, 

 cheese cloth was fastened to the ground with spikes below a 

 sprayed tree, so that the insects which succumbed to the effects 

 of the poisoned sweet and dropped from the tree, could be 

 detected more easily on a white background. By gathering the 

 dead specimens daily, we endeavored to determine how long 

 the spray was effective after different amounts of rainfall, ani 

 thus secure a. clue as to the minimum number of applications 

 necessary to insure good results. 



Experiment I. In the first experiment one each of the fol- 

 lowing apple trees, Duchess, Fameuse, Mcintosh Red, Tolman 

 Sweet and three plum trees were treated with the fruit fly 

 remedy, which was prepared according to the same formula 

 Illingworth used in 191 1. One pint to two quarts of the insec- 

 ticide, depending upon the size of the tree, was applied to the 

 foliage and fruit on July 11. The sprayed leaves on all of 

 these trees were scorched and on July 16, some of these leaves 

 began to drop. The fruit was examined from time to time 

 and occasionally traces of burning was found but this was es- 

 pecially marked with the Duchess. A large number of dead 



