SOLUBLE POISONS IN THE POISONED BAIT SPRAY. l6l 



21, two days after spraying, one dead fly was picked up on the 

 cheese cloth and on August 24, the last trypetid was found, but 

 due to heavy rains during the preceding day we were unable 

 to visit the tree. A light shower of rain fell on August 22, but 

 heavy rains fell during the night and continued throughout the 

 next day. The precipitation amounted to 1.58 inches on August 

 23, and the last baiting in the entire experimental area became 

 ineffective after this date. 



We have already called attention to two different methods of 

 applying the spray. After the above Benoni tree received three 

 applications of the bait, by spraying the trunk, larger limbs and 

 foliage of the lower branches, 88 per cent* of the apples were 

 found to be infested on August 19. On this same date, the 

 fourth treatment was given by forcing the poisoned sweet from 

 the spray pump into the air toward the top of the tree, so that 

 the minute drops fell over and in the tree. On September 2, 

 49 per cent* of the apples were maggoty and on September 22, 

 15 per cent* were infested. In all probability, a general dis- 

 tribution of the fruit fly remedy over the foliage is more effec- 

 tive than spraying the trunk and large limbs due to the fact 

 that the bark seems to absorb the ipoisoned diluted molasses. 

 After the water has evaporated, a glossy layer of molasses ad- 

 heres to the upper surface of the leaves, while the hairy coating 

 of the lower epidermis prevents the formation of this film oi 

 sweet and seemingly absorbs a considerable amount of the 

 poisoned liquid. 



Attraction to poisoned bait. One observation tends to show 

 that the apple fruit fly is attracted to the poisoned bait under 

 field conditions. A specimen was observed at rest on an apple 

 just at the time that the spray was about to be applied to the 

 tree. Suddenly the fly took wing and came to rest on my hand 

 which was spattered with the bait and here it began to feed. The 

 distance from the apple to my hand was about a yard. 



Checking up results. In checking up the effectiveness of the 

 poisoned bait spray, the apples were picked at random from a 

 treated tree in the various orchards or residential district and 

 on the same day apples of a similar variety were gathered from 



♦This sequence of per cents is of course only possible where the 

 infested fruit is dropping and the counts taken each time from fruit 

 remaining upon the tree. 



