INSECTICIDES AND THEIR USES 33 



White arsenic (pure arsenious acid) is the active principle 

 of all the arsenicals. It is particularly dangerous when used 

 alone in solution, but as it is the cheapest of the arsenicals it is 

 employed in the preparation of poisoned baits for cutworms and 

 grasshoppers. Combined with lime it forms arsenitc of lime. 



Arsenite of lime has been highly recommended by those who 

 have tried it. It is prepared by such methods as follow : 



The Kedzie formula : Boil 2 pounds of white arsenic and 8 

 pounds of sal-soda 15 minutes in 2 gallons of water. Put into 

 a jug, label "poison" and lock it up. When ready to spray, 

 slake 2 pounds lime and stir into it 40 gallons water, adding 

 a pint to a quart of the mixture from the jug. 



Formula No. 2 : Boil together i pound white arsenic, 2 pounds 

 lump or stone lime and 3 gallons water. Dilute with about 

 200 gallons of water before spraying. 



Still other arsenicals possess insecticidal properties. Of these 

 "pink arsenoid" has given good results experimentally. "White 

 arsenoid" has been practically withdrawn from the market. 

 "Paragrene" is reported as having equal insecticide value with 

 Paris green, is about as likely to burn foliage, but remains 

 longer in suspension.^ 



The arsenicals are also useful in the preparation of poisoned 

 baits, which will be discussed in the consideration of cutworms 

 and locusts or grasshoppers. 



Harnilessness of arsenicals when properly applied. — Chemical 

 analysis has shown that cabbage which has been dusted or 

 sprayed with an arsenical in the way prescribed, and then 

 prepared for cooking in the usual manner a week later has not 

 even a trace of arsenic remaining. The use of arsenicals against 

 cabbage worms is almost universal, although growers are some- 

 times loath to acknowledge the fact for fear of the loss of 

 customers who are not fully acquainted with the harmlessness 



More detailed directions for the preparation of the arsenicals here dis- 

 cussed are given in Farmers' Bulletin 127, U. S. Department of Agriculture. 



