548 



NEW YORK STATE MUSEUM 



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 

 June 6 



Five caterpillars were put in a jar 

 with maple leaves sprayed with 1 lb. 

 paris green to 200 gal. water. 



Five caterpillars were put in a jar 

 with leaves sprayed with 4 oz. soda 

 arsenate and 11 oz. lead acetate to 

 160 gal. 



8 



2 dead, 1 apparently dying, leaves 

 comparatively fresh. Caterpillars 

 have fed considerably. 



1 nearly dead, caterpillars have fed 

 only a little. 



9 



1 lively, 1 spun up, 1 nearly dead, 

 leaves much wilted. 



1 dead, 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. 



