PARIS-GREEN. 353 



" For general use on mature foliage : — j lb. of Paris-green, 

 50 gallons of water." First mix the Paris-green separately 

 with a small quantity of water, then add to it the whole sujoply. 

 All washes containing Paris-green must be constantly stirred 

 to keep it in suspension, or it will sink to the bottom.* 



At first here, as elsewhere, some difficulties in application 

 of a new kind of treatment are likely to occur ; if too strong, 

 or the mixture not evenly distributed, the leafage 2vill he, if 

 too weak the caterpillar will not he, hurt ; but the great point 

 in first experiment is to be sure that the mixture is 7iot too 

 stroiuj. If too weak, this mistake is easily corrected, and it 

 would be best to try a pailful at first on a tree or two than to 

 risk more. Also it is advised that it should be used in dry 

 weather, or necessarily the application may be washed away ; 

 and likewise it is to be remembered that Paris-green is 

 insoluble ; it does not dissolve in water, but mixes with it, so 

 unless the mixture is kept stirred, or by some means or other 

 in movement, the powder will settle down at the bottom of the 

 water. 



The spray should be applied so as to reach all parts of the 

 tree and both sides of the leaves, and should be sent so that it 

 may coat the leaves as with a fine dew, not run down and drip. 

 As soon as dripping begins spraying should cease. 



It should not be done whilst the trees are in blossom, and 

 warning is also given in the American works that sprayings 

 should not be given in rapid succession. Several days, it is 

 advised, should elapse between, unless of course, as may easily 

 happen in difficulties of first experiments, the spray was 

 manifestly so weak that the application counted for nothing. 

 The effect of the Paris-green on the caterpillars does not 

 always show directly, and it is undesirable to waste labour and 

 material where the work is already done, and only requires a 

 day or two to show it. 



The following advice was kindly sent me for use in the 

 experiments of our Evesham Fruit Conference, in addition to 

 much other serviceable information which was placed in our 

 hands by the Entomologist of the Dominion of Canada. 



Mr. Fletcher wrote me on Feb. 28th, 1890 :— 



" Paris-green : — You are quite safe in recommending this ; 

 but insist upon these two things, viz., 1st, to keep the mixture 

 (which is a mixture, not a solution) well stirred all the time, 

 and have the barrel well washed out after it has been filled 

 ten or twelve times. The Paris-green is very heavy, and will 

 keep sinking to the bottom unless constantly agitated, and as 

 the barrel is frequently re-filled the residue will keep accumu- 



* 'Eeport of Entomologist, Central Experimental Farm, Department of 

 Agriculture, Canada,' 1887, p. 21. 



