WINTER MOTH ; PARIS, OR EMERALD GREEN. 171 



In application of Paris-green sprayings, it must always he 

 borne in mind tJtat, tvhatever kind of engine or spraying machine 

 is vsed, the mixture must he kept an even strength throughout, 

 mid no sediment allowed to form at the hottoni, or damage to 

 leafage is sure to happen. 



On these points Mr. Fletcher, the Dominion Entomologist 

 of Canada, wrote to me as follows, and also enforcing care as 

 to over-application : — 



^^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 accumulating, 

 until it will be too strong as the mixture reaches the bottom. 

 2ndly. The other point is to insist upon the mixture not heing 

 made too strong ; 1 Ih. to 200 gallons I find very useful, and I 

 never use stronger than 1 Ih. to 120 gallons.'" — (J. F.) 



With regard to method of application of the spray. — This 

 should be thrown so finely as to reach all parts of the tree 

 and both sides of the leaves, and coat the leaves as with a 

 fine dew, but it should not be allowed to run down and drip. 

 As soon as dripping begins spraying should cease. 



It should on no account tvhatever he throivn so as to " swill " 

 or "souse" the trees, and run off the leaves in drops or 

 streams ; this is bad practice in every way. It uses a great 

 deal more of the chemical than is needed; the leaves get little 

 but pure water at their highest part, and much too strong 

 application where the fluid has settled at the tips ; and also 

 a drip is caused on to the ground beneath, which may render 

 the grass temporarily poisonous. 



Also, spraying should not he done whilst the trees are in 

 hlossom, 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 experi- 

 ments, the spray was manifestly so weak that the previous 

 application counted for nothing. The efiect 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. 



In mixing and in the use of Paris-green as a fluid dressing, 

 or spray, one of the first points to be borne in mind is that 

 this chemical does not dissolve in water. It is simply held in 

 suspension; the following is a good recipe for mixing so as to 

 ensure the powder and water being thoroughly mixed to start 



