THE CANADIAN ENTOMOLOGIST 



309 



A REVIEW OF THE WORK ON THE POISONED BAIT 



SPRAY, DRY METHOD AND MIXED TREATMENT 



OF CONTROLLING FRUIT FLIES (TRYPETID^E). 



BY HENRY H. P. SEVERIN, PH. D., MILWAUKEE, WIS. 



(Continued from p. 284). 



Mixed Treatment. 

 The mixed treatment is a combination of the spray and a dry- 

 method of control. The object of this method is to reduce the 

 number of applications of the spray. One sac was placed in every 

 fifth tree. Two applications of the spray were made during the 

 entire season. The following formula was used: 



Molasses 100 kilogr. 



Sodium arsenate 2 



This stock solution was diluted by adding 100 liters of water to 

 15-20 kilogrammes of the poisoned molasses. About 1 pint of this 

 solution was applied to a tree. The cost of the mixed treatment 

 amounted to $2.00 per tree. This method was carried on during 

 three successive seasons and the results are recorded in table VIII. 



TABLE VIII. 



The difference in favour of the mixed treatment is apparent, 

 but not satisfactory in all cases. The authors state that the 

 poisoned bait is not so effective in olive gardens containing culti- 

 vated shrubs or where the olive grove is near a wood, for the 

 olive fly probably secures shelter and nourishment from the nectar 

 of flowers and sweetened exudation of herbaceous organs. On the 

 other hand, in localities where the orchard is isolated and contains 

 only olive trees, the fly is content with its shelter and seeks nourish- 

 ment here, and the poisoned bait then produces its maximum effect. 



Table VIII shows the effect produced by omitting the treat- 

 ment for one year. In 1909, from 2 to 2.5% of the olives were 

 maggoty from 550 trees which had received the mixed treatment. 

 In 1910, the same 550 trees which are now included in the 1.200 



September, 1914 



