ARSEI^ATE OF LEAD AS AN mSECTI- 



CIDE. 



C. H. FERNALD, ENTOMOLOGIST. 



In the work of destroying the gypsy moth it was soon 

 discovered that Paris green would not kill many of the cater- 

 pillars, even when used in as large a proportion in water as 

 was possible without injury to the foliage of the trees. It 

 therefore seemed necessary to discover, if possible, some 

 insecticide that would destroy the caterpillars and at the same 

 time not injure the most delicate foliage. Mr. F. C. Moul- 

 ton, who was employed by the gypsy moth committee as 

 chemist, was directed to investigate the various compounds 

 of arsenic, and endeavor to find some substitute for the insec- 

 ticides then in use which possessed the necessary proper- 

 ties. After a long series of experiments, in 1892 he was so 

 fortunate as to discover arsenate of lead, which certainly 

 possesses the desirable characteristics more fully than any 

 insecticide previously known. 



The first public mention of arsenate of lead was made in 

 the report of the Massachusetts Agricultural College, Octo- 

 ber, 1893, p. 23. In Bulletin No. 24 of the Hatch Experi- 

 ment Station, Amherst, Mass., published in April, 1894, a 

 more complete account was given of this insecticide and of 

 experiments with it on the tent caterpillar and Colorado 

 potato beetle. Mention was also made of this insecticide 

 under the name of ' ' gypsine " in the report of the gypsy 

 moth committee for 1894, pp. 20 and 35. The name "gyp- 

 sine " was given to this insecticide by Mr. Moulton, but, as 

 there was an entirely different product on the market by the 

 same name, this insecticide was called arsenate of lead, to 

 avoid confusion. In the report of the gypsy moth commit- 

 tee, February, 1894, p. 20, the announcement of the dis- 

 covery of arsenate of lead by F. C. Moulton was made by 

 Mr. E. H. Forbush, the field director, and the formula was 

 given. In the same year Prof. James Fletcher, in " Evi- 



