492 PREVENTION AND DESTRUCTION OF INSECT PESTS. 



failures here have been due to its careless use, and by the users not 

 understanding the methods of applying the wash. Arsenate of lead 

 is mixed in the following manner : dissolve 4 ounces of arsenate of 

 soda (40 to 50 per cent strength) in a little water, then dissolve 12 

 ounces of acetate of lead (white commercial) also in water. Add 

 the arsenate of soda to 100 gallons of water, and then after stirring 

 well add the dissolved acetate of lead and mix the whole well 

 together. To test its safety, filter some of the wash and add 

 arsenate of soda, when a faint white precipitate should be given. 

 It should give no precipitate with acetate of lead. If properly 

 mixed, even the concentrated form will not damage the leafage. 

 The addition of treacle or soft-soap greatly enhances its value, 

 causing it to stick to the leaves. Reports sent in to me are, 

 however, very variable, many growers finding it not nearly so 

 good as Paris green, some quite useless, others a most deadly 

 wash ; personally I have found it very successful.' Paris green 

 is used at the rate of 1 lb. to 200 gallons of water for apple and 

 pear trees and other fruit, except peach and nectarine, where 1 lb. 

 to 300 gallons is quite sufficient. It is best obtained in the form of 

 paste and not powder. It has to be employed with care, as it has a 

 tendency to bum the edges of the leaves if put on too heavily and 

 not properly mixed. The addition of a little lime greatly increases 

 its safety. Similar remarks ajjply to London piu'ple. The im- 

 portant things to remember in regard to the use of these washes 

 are as follows : The wash must be evenly and accurately mixed. The 

 trees must be sprayed with asfiiie a spray as possible. , Proper instru- 

 ments for s'praying should be used. Two or three slight sprayings are 

 better than one drenching ; many failures have been due to the too 

 liberal use of these washes. Never spray when the sun is out, or the 

 leafage will get scorched. Spray in early morning and late in the 

 afternoon. Never spray when the blossom is out, as it damages the 

 blossom and kills the bees. Never leave the washes about, as they 

 are poisonous. Three washes should be always employed — ojie just 

 before tlie buds begin to burst, the second just before the blossom opens, 

 and the third directly the blossom has fallen. By so doing three 

 insect attacks are dealt with — namely, winter moth, apple weevil, 

 and codlin moth. 



2. Eesin washes are used for scale insects (Goccidai) : their object 

 is to fix the scale to the plant in the early spring, and so prevent the 



1 In Massachusetts (U.S.A.) it has heen most successfully employed in 

 comhating the plague of Gypsy Moth caterpillars. 



