The Currant Fruit Fly. 



231 



white back ground. The results with each formula of the poi- 

 soned bait used in the various experiments are given in detail 

 as follows : 



In the first experiment we endeavored to determine what 

 effect arsenate of lead (paste) without molasses would have on 

 the pest. After a light application of the spray was made to 

 the foliage of a gooseberry bush, 50 fruit flies were liberated 

 in the cage. Many of the specimens rested on the sides and top 

 of the cage. The formula employed and the daily death rate of 

 the flies are given in table 27. 



TABLE 27. 



Death Rate of Adults Confined in Cages Enclosing Gooseberry 

 Bushes Sprayed With Arsenate of Lead or Poisoned Bait. 



Molasses 



Arsenate 

 of Lead 



(oz.) 



Water 

 (gal.) 



Death Rate of Flies 





(pt.) 



1 i ■ 2 



3 



5 



Days 





1 

 1 



2 



1 



1 

 1 



1 It 



14 12 

 19 5 



3 

 3 



8 



1 



Flies 

 Flies 

 Flies 



As ants were found in the cage devouring and carrying 

 away dead fruit flies, the daily record of the death rate is prob- 

 ably not correct. Living flies were found within the cage at tlie 

 end of 5 days, when the experiment was discontinued. 



To determine whether the fruit fly would feed on arsenate 

 of lead after the water had evaporated, a twig was cut from the 

 sprayed bush, three days after the application of the insecticide, 

 and the stem was emersed in a bottle of water within a glass 

 jar. One fly died at the end of one day, but 24 specimens were 

 still alive at the end of 6 days, when the experiment was discon- 

 tinued.. During the 6 days the cheese cloth covering the top of 

 the jar was moistened with diluted corn syrup and water, sev- 

 eral times a day. It was evident that arsenate of lead when dry 

 on the leaves had no marked effect on the fruit flies in captivity 

 under laboratory conditions. 



In the next two experiments different quantities of arsenate 

 of lead were added to diluted molasses and the different formu- 

 las of the poisoned bait were then tested under field conditions. 

 To prevent the ants from entering the cages through the mos- 



