548 ae NEW YORK STATE MUSEUM ~ Rae: 
The above record shows that arsenate of lead is slower in action than 
either of the other poisons and that.in this experiment the smaller 
amount of the arsenate was fully as effective as the larger. Examina- 
tions showed that apparently more of the foliage was eaten in no. 5 than 
in no. 4, and if that be the case, the apparent anomaly may be explained, 
as the beetles in no. 5 probably got a fatal dose as soon as those in no. 4, 
in spite of the fact that in no. 4 the poison was double strength. Though 
the arsenate of lead operates more slowly, it was clearly shown by last 
summer’s experience in the field that when the application was thorough 
and timely, shade trees suffered very little from attacks by the elm leaf 
beetle, and as this poison remains an indefinite time on the foliage it can 
hardly be surpassed as a substance for controlling such an insect as this 
elm pest, which feeds for a considerable part of the growing season. 
The following record of an experiment with nearly full grown forest 
tent caterpillars shows that this species can be controlled with a poisonous 
spray even when the caterpillars are full grown. It also illustrates the 
effective, though somewhat slower action of arsenate of lead. 
EXPERIMENTS WITH FOREST TENT CATERPILLAR - 
1899 Five caterpillars were put in a jar | Five caterpillars were put in a jar 
June 6 with maple leaves sprayed with 1 Ib. with leaves sprayed with 4 oz. soda 
paris green to 200 gal. water. arsenate and 11 oz. lead acetate to 
160 gal. 

8 | 2 dead, i apparently dying, leaves | 1 nearly dead, caterpillars have fed 
comparatively fresh. Caterpillars only a little. 
have fed considerably. 


9,1 lively, 1 spun up, 1 nearly dead, | 1 dead, leaves much wilted. 
leaves much wilted. 

10 | Freshly sprayed leaves were supplied. | 1 spun up. Freshly sprayed leaves 
were supplied. 



12 | 2 dead. ‘| 1 dead, 1 lively, 1 spun up. 

Moth never emerged. Moths never emerged. 

Some maple trees in Albany badly infested with forest tent caterpillars 
were sprayed on May 22 with W. H. Swift & Co.’s preparation of 
arsenate of lead and on the 27th dead caterpillars were abundant on the 
trees and around the base of the trunks, a striking illustration of the 
effectiveness of this poison. Further, I have elm leaves which were last 
sprayed May 22 and on October 25, after they had fallen, the poison was 
found in considerable quantity on them, showing the adhesiveness of the 
preparation. 
