DIVISION OF ENTOMOLOGY. 



C. H. Fernald. 



During the past season a scries of experiments was performed with 

 various insecticides on some of our common and troublesome insects, 

 for the purpose of determining what proportions could be used to 

 destroy the insects without injury to the foliage. 



A NEW INSECTICIDE. 



ARSENATE OF LEAD. 



This substance was first proposed as an insecticide by Mr. F. C. 

 Moulton, in 1892, while acting as chemist in Maiden, under Mr. E. 

 H. Forbush, Field Director, in charge of the work of destroying the 

 gypsy moth. 



The formula generally used in its preparation was arsenate of soda 

 29.93 per cent and acetate of lead 70.07 per cent by weight. These 

 substances were weighed out separately and put into a hogshead con- 

 taining 150 gallons of water, when chemical reaction took place which 

 resulted in the formation of arsenate of lead, a very fine, white precip- 

 itate which is much lighter than Paris green. 



A series of experiments was performed with this substance on the 

 tent caterpillar {Clisiocampa americana) , in proportions varying 

 from i lb. to 150 gal. of water, to 24 lb. to 150 gal., and in no case 

 was the foliage injured. 



