246 INJURIOUS AND USEFUL INSECTS 



Arsenicals are applied as spray, or, in the case of certain low 

 plants not immediately to be eaten, as a dry powder. The 

 mixture used in spraying is i lb. to 100-250 gallons of water 

 (= I : 1000-2500). I lb. to 150 gallons (i : 1500) is a good 

 strength for general purposes. The stronger mixtures are for 

 such foliage as that of the potato, and the greater dilutions 

 for the more tender foliage of the peach or plum. The poison 

 should be first made into a thin paste with a small quantity of 

 water, an equal amount of quicklime being added to take up 

 free arsenic, and remove or lessen the danger of scalding. An 

 excess of lime will do no harm. The poisons thus mixed 

 should be strained into the spray-tank or reservoir, care being 

 taken that all the poison is pulverised and washed through the 

 meshes of the strainer. The use of the lime is especially desir- 

 able in the case of the peach and plum, the foliage of which, 

 particularly the former, is very tender and easily scalded. To 

 the stronger foliage of the apple and most shade-trees Paris 

 green may be applied without danger at the strength of i lb. 

 to 1 50 gallons of water. 



The arsenate of lead is prepared by carefully pulverising and 

 combining, in a small quantity of water, the weight of the two 

 ingredients indicated by the capacity of the spray-tank. The 

 chemical combination is effected in a few minutes, and the 

 resulting milky mixture is ready for the tank. Lime is not 

 needed with this arsenical. 



It must be remembered that these arsenicals are very 

 poisonous and should be so labelled. If ordinary precautions 

 are taken there is no danger to man or team attending their 

 application. With some individuals the arsenate of lead, when 

 in strong mixture, affects the eyes ; but this is unusual, and, 

 with a little care in spraying, the mist need not strike the 

 operator at all. 



The poison disappears from the plants almost completely 

 within twenty to twenty-five days, and even if the plants were 

 consumed shortly after the application an impossible quantity 

 would have to be consumed to get a poisonous dose. To 

 illustrate, in the case of the apple, if the entire fruit were eaten, 

 core and all, it would take several barrels at a single sitting to 

 make a poisonous dose (Riley), and with the cabbage, dusted 

 as recommended above, twenty-eight heads would have to be 

 eaten at one meal to reach this result (Gillette). It is prefer- 



