THE CANADIAN ENTOMOLOGIST. 



279 



The Italian entomologists obtained excellent results in small, non- 

 isolated olive groves by applying 6-7 sprays. It would be necessary 

 to renew the bait after each heavy rain. 



In the large, non-isolated olive groves the central part is pro- 

 tected by the spray, while the fruit along the periphery is generally 

 attacked by the maggot in a proportion which increases according 

 to the nearness of the infested olive plantations not treated. 



Isolated orchards. — During a number of seasons Chapelle (2) 

 and Ruby conducted a series of spraying experiments in small, 

 isolated olive gardens. In one experiment 620 trees were sprayed 

 during two successive seasons. This orchard was isolated by about 

 one kilometer (3,280.8 feet) from other olive groves. The results 

 obtained are given in Table VI. 



Olive groves containing 10,000 trees were treated with the dry 

 method of control in 1911 (Table VII) and with the poisoned bait 

 spray in 1912. These olive gardens were scattered over a large 

 area, and were owned by a score of proprietors. The vast area of 

 olive trees was well isolated, being situated at a distance of 500-600 

 meters from the neighbouring olive plantations. 



The insecticide was composed of 15 kilogrammes of molasses, 

 2H% °f sodium arsenate in 100 liters of water. One application 

 of the spray was made on July 8, just previous to the emergence of 

 the first brood of olive flies, and another treatment was given on 

 September 6, at the time when the second brood of flies were issu- 

 ing. The second spray was applied to the more exposed parts of 

 the large area of olive trees, only two-thirds of the orchard being 

 treated. One man was able to spray 700-900 trees in a day. Each 

 tree received about .3-. 4 of a liter of the bait. The cost of the 

 treatment, including labour, was estimated at 1 cent per tree. The 

 results of examining the crop on October 5 and November 5 are 

 recorded in Table IV. 



TABLE IV 



