1912.] PUBLIC DOCUMENT — No. 31. 177 



THE CHEMISTRY OF ARSENICAL 

 INSECTICIDES. 



BY E. B. HOLLAND AND J. C. REED. 



General Introduction. 



The work on arsenical insecticides, at the chemical laboratory 

 of this station, has advanced sufficiently to warrant a second 

 report ^ on the subject dealing particularly in this instance with 

 the composition, manufacture and use of Paris green, lime 

 arsenite and lead arsenate. In this connection it may be of 

 interest to consider briefly the monetary loss resulting from 

 injurious insects, and note the insecticides available to check 

 their depredations previous to the introduction of arsenicals. 



The aggregate loss in the United States from insect injury 

 to agricultural products of all kinds including live stock, forest 

 and shade trees and ornamental plants, together with the subse- 

 quent damage to manufactured goods, is impossible to compute 

 with any degree of accuracy. It has been estimated ", however, 

 at $1,000,000,000 annually, and may exceed that amount. 

 Without question the successful production of many, if not most, 

 crops is dependent in a large measure upon their protection 

 from noxious insects. The rapidity with which such pests mul- 

 tiply and are disseminated, and the readiness with which they 

 adapt themselves to new conditions, occasionally undergoing 

 considerable change in character, size and appearance, demands 

 thorough scientific treatment for their control, as eradication is 

 practically impossible. The tendency of injurious insects to 

 feed on a greater variety of plants and to become more destruc- 

 tive in a new country than where indigenous, due to more favor- 

 able climatic conditions or absence of natural enemies, renders 

 the problem even more difficult to handle. 



■First report in Mass. Exp. Sta. Rept., 23, p. 122 (lOU), entitled The Determination of 

 Arsenic in Insecticides. 



3 Economic entomologists allow 10 per cent. loss on all produce. 



