INSECTICIDES IN GENERAL: STOMACH POISONS 47 



A standard formula for arsenate of lead is: 



Per Barrel Per Gallon 



Arsenate of lead paste 3 lb. 3 teaspoonfuls (level) 



Water 50 gal. 1 gal. 



Arsenate of lead powder 1}.^ Ih. 9}4 teaspoonfuls (level) 



AVater 50 gal. 1 gal. 



In mixing the paste it is w^oll to add some water antl stir thoroughly 

 before adding the rest of the water, in order to get a more uniform mix- 

 ture. If it is allowed to dry it will not work up well thereafter by adding 

 water, and it is also injured by freezing. 



Arsenate of Lime. — This substance has come into use since about 

 1914, because of the rapidly increasing cost of arsenate of lead. It 

 is Ca3(As04)2 and may be obtained, like arsenate of lead, either as a paste 

 or a powder. The former contains about 18 per cenj: of arsenic oxid, 

 and the latter about 44 per cent, thus being slightly higher in paste form, 

 and considerably higher in powder form, than arsenate of lead. As the 

 costs of the two forms differ correspondingly, there is little choice between 

 them from this standpoint, but convenience and other factors give a slight 

 preference to the powder. Being stronger than arsenate of lead, less 

 needs to be used in order to supply an equal amount of poison to a given 

 area. 



Arsenate of lime is not safe for use on foliage, and particularly that of 

 stone fruits, unless an excess of lime is present. Accordingly, as was the 

 case with Paris green, lime must be added to the mixture. 



A standard formula for arsenate of lime is: 



Pek Baruel Per (Jallon 



Arsenate of lime paste 2 lb. 13'2 teaspoonfuls 



Quick lime 2 to 3 lb. 2 teaspoonfuls 



Water 50 gal. 1 gal. 



Arsenate of lime powder ^i lb. 4f^ teaspoonfuls 



Quick lime 1 lb. 9 teaspoonfuls 



Water 50 gal. 1 gal. 



The quick lime, which should be fresh stone lime, is slaked in some of 

 the water, then added to the rest, and the arsenate of lime thoroughly 

 stirred in. 



While this material is cheaper than arsenat(i of lead and perhaps 

 kills a little more quickly, it has not been in use long enough to be certain 

 just what results may be expected in all cases. At least it may at the 

 present time be termed a very promising insecticide. 



Poison Baits. — These are included here, as, in most cases at least, 

 they contain an arsenical poison. They are used mainly for the control 

 of cutworms and grasshoppers. There are several formulas proposed. 



