MISCELLANEOUS INSECTICIDE INVESTIGATIONS. 11 



moderate burning on the bean, about 25 per cent of the leaves being 

 shed, but no burning where it was combined with lime or lime- 

 sulphur. The commercial (3) produced no burning on bean foliage 

 and very slight burning on peach foliage. 



Arsenate of calcium, c. p., caused about 15 per cent of the leaves 

 to drop on peach, but had no burning effect on bean foliage. 



The arsenates of iron, chemically pure and homemade, did not 

 burn either bean or peach foliage. 



Arsenate of zinc, c. p., did not burn bean foliage, but seriously 

 injured peach foliage, causing complete defoliation. The home- 

 made form of arsenate of zinc produced very slight burning on peach 

 and no burning on bean foliage. 



Arsenic sulphid produced severe burning in all tests. 



Arsenic tersulphid produced the same results as arsenic sulphid. 



Arsenic trioxid burned severely in all cases except when com- 

 bined with lime, in which case the burning was slightly less. 



Arsenite of lime, homemade, burned the bean foliage moderately 

 when used alone and in combination with lime-sulphur. However, 

 no burning resulted when extra lime was added. The peach foliage 

 was severely burned by this material, causing all the leaves to drop. 



Arsenite of zinc (1), chemically pure, burned severely in all cases 

 except where lime was used, in which case no burning resulted. 



Arsenite of zinc powder, commercial (2), burned moderately on 

 beans except where lime was added, in which case no burning resulted. 

 It caused all of the peach leaves to drop. Arsenite of zinc, commercial 

 (3) and commercial (4), gave the same results. 



Paris green produced moderate burning in all the tests on bean 

 foliage and burned all the leaves off the peach. 



EXPERIMENTS, 1913. 



LABORATORY TESTS. 



Several poisons, namely, arsenate of lead paste, commercial; two 

 commercial brands of powdered arsenate of lead; arsenate of calcium, 

 commercial; two forms of arsenate of calcium, homemade; arsenate 

 of zinc, homemade, and arsenite of zinc, homemade, were tested against 

 the larvee of several different species of chewing insects. 



The arsenates of lead and the arsenite of zinc were used at the 

 strengths recommended by the manufacturers. Arsenate of cal- 

 cium, commercial paste, was used at the rate of 1 J pounds to 50 gal- 

 lons of water. Arsenate of zinc, homemade, was prepared and used 

 as given on page 2. Arsenate of calcium (1) was prepared by dis- 

 solving 1 pound of sodium arsenate and 1 pound of calcium acetate 

 each in 1 gallon of hot water and pouring them together slowly, at 

 the same time stirring the solution vigorously. This was used at a 

 strength equivalent to 0.8 pound of sodium arsenate to 50 gallons of 



