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and other insects on fruit trees is considered by those 

 who have worked with it, the most efficacious treatment, 

 and is now superceding the use of washes. When it is 

 remembered that many of these scale insects are pro- 

 tected by a shell, not unlike a minute turtle's shell, all 

 the limbs and other parts being small and concealed, 

 and that the edges of this are commonly kept closely ap- 

 plied to the leaves or twigs it will be understood that it 

 is no easy matter to apply fluids by spraying so as to 

 reach vulnerable parts of these insects. It is true, none 

 the less, that the resin compounds and preparations of 

 kerosene are very useful for this purpose, especially 

 where the number of trees to be treated is small, and ap- 

 plications can thus be made repeatedly and thoroughly. 



Gas, however, penetrating as it does every crevice 

 about the trees is calculated to destroy all insects it 

 reaches, and experiment shows that it will destroy their 

 €ggs as, well. In applying the gas it is, of course, essen- 

 tial that the trees be enclosed. For this purpose Mr. Co- 

 quillett recommends large octagonal sheets made in great 

 part of eight ounce duck, the two middle breadths upon 

 which the strain comes in handling, being made of ten 

 ounce duck. These may be rendered gas-tight by paint- 

 ing with linseed oil, or a thin paint made of yellow ochre, 

 and are placed over small trees by means of poles, or 

 over large ones by means of a special derrick mounted 

 on a wagon. 



The hydrocyanic acid gas, now generally employed, is 

 generated in an open earthen vessel placed under the 

 enclosing tent or sheet . The ingredients employed are : 

 Undiluted commercial sulphuric acid, 1 fluid cz. ; undis- 

 solved, fused potassium cyanide, 1 oz. by weight ; cold 

 water, 3 fluid ounces. The water is poured into the ves- 

 sel, then the acid follows, after which the vessel is placed 

 on the ground in the tent, and the potassium is added, 



