284 



THE CANADIAN ENTOMOLOGIST. 



iron pan (about 14-20 inches in diameter; 6-8 inches deep) con- 

 taining the poisoned molasses. Pieces of rags floating at the 

 surface of the poisonous mixture, enable the insect to come to rest 

 within reach of the bait. Each pan contained about 2 kilo- 

 grammes of poisoned molasses (3% arsenate of soda) diluted with 

 a small quantity of water. The evaporation during the dry sum- 

 mer caused the molasses to lose its syrupy state and 2 liters of 

 grape juice were added to each pan. In 1910 this dry method of 

 control was undertaken in two isolated olive gardens. A glance at 

 table VII shows the results obtained, 



During this same year, this method was tested on a large 

 scale in Italy under the direction of Dr. Berlese. The results as 

 published by this scientist were most favourable. 



In 1911, Chapelle (2) and Ruby repeated the experiment on a 

 large scale. A score of olive groves containing 10,000 trees was 

 selected. This large area of olive trees was isolated by 500-600 

 meters from the neighbouring olive plantations. The pans were 

 regularly distributed at the rate of 1 for every 40 trees. Each pan 

 cont lined from 5-6 liters of the following solution: 



Molasses 15 kilogr. 



Sodium arsenate 3 



Salt water 100 liters 



From the beginning of summer up to the first rains of autumn, 6 

 liters of water was poured into each pan. The results are shown 

 in table VII. 



TABLE VII. 



1910 

 1910 

 1911 



Number of 

 pans. 



13 

 80 



250 



Number of 

 trees. 



020 

 3,000 

 10.000 



Olives infested in treated 

 orchard. 



Olives infested in untreated 

 orchard. 



Vo 

 25.66 

 1.66 

 14.1 



-14.67 



to 



is. Ill 

 8.0 

 7.0 



2.S 

 S.O 



1.32 



Vo 



According to the figures in the above table the treatment with 

 the use of the pans has no practical value. 



The three systems classed under the dry method of control 

 as practised by the French entomologists have not given as 

 satisfactory results as the poisoned bait spray. 



(To be continued. 



