DISEASES OF THE OLIVE TREE ] 115 



the pupae In the soil are killed by frequent irrigation and 

 tillage, and as the olive- fly does not attack other fruits, 

 there is not the possibility that the insect may come 

 over from orchards in the neighbourhood. 



The remedies proposed against the olive-fly are the 

 following: 



A. Remedies directed against the winged insect. In 

 1762 it was proposed by Seuve to attract and poison the 

 fly by means of a sweet and poisonous mixture moistened 

 with water, As a poison Seuve proposed orpiment in 

 powder (sulphide of arsenic). The Royal Experimental 

 Station of Florence proposes a mixture of treacle or 

 molasses 70 parts (by weight), water 28 parts and 

 arseniate of sodium 2 parts. The water is raised to the 

 boiling point, and the arseniate of sodium is dissolved 

 in it, the molasses are then added gradually, constantly 

 stirring the mixture to obtain a uniform distribution of 

 the poison. Instead of water others recommend the use 

 of the juice of grapes in the proportion of 50 parts of 

 molasses, 48 parts of juice of grapes and 2 parts of 

 arseniate of sodium. The mixture may be sprayed on 

 the tree duly diluted but is best used by daubing it here 

 and there on the large branches by means of a brush. 

 This method is said to give fairly satisfactory results. 



B. Remedies directed against the Larva and the 

 chrysalis. 



1. Pick up at once all dropped olives giving no 

 time to the larva to come out and hide in the ground. 



2. Dig the ground under the trees deeply at least 

 twice during the breeding season of the fly, the object 

 being to bury the larva and the pupae at a depth whence 

 the winged insect will have little chance to come up. 



3. Scrape away all the dead and fissured bark of 

 old trees, and cover the trunk and large branches with a 

 strong solution of sulphate of iron (green vitriol), i to 2 

 kilos of green vitriol to 100 litres of water, applied by 



