366 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



in relation to plant as well as animal life. While no positive state- 

 ments are possible owing to lack of sufficient data, 65 milligrams of 

 arsenous oxide (white arsenic) to 1,000 grams of live weight may- 

 approximate the toxic dose 1 for the horse, ox, sheep and fowl, and 9 

 milligrams for the dog and pig. On the former basis of susceptibility, 

 65 milligrams of arsenous oxide (equivalent chemically to 76 milligrams 

 of As 2 5 ) would kill 1,000 grams (net weight) of bees or 12,658 individual 

 workers 2 weighing 79 milligrams each, or on the latter basis of sus- 

 ceptibility, 9 milligrams of arsenous oxide would accomplish the same 

 results. The toxic dose for bees is unquestionably small, whatever the 

 figure, as a considerable portion of the arsenic detected in the samples 

 was evidently in the bee load and not assimilated as shown by the 

 following treatment. A lot of bees containing arsenic, after being 

 shaken with 1 per cent nitric acid for 1 minute and rinsed twice with 

 water, gave only a "possible trace" of arsenic. Another portion 

 treated similarly with 3 per cent nitric acid would no longer react. 

 The use of 3 per cent acid proved inadvisable, however, as it was 

 found too active for even so short a period. The above test would 

 indicate that bees are susceptible to even less arsenic than is detected 

 in the original samples. 



The work will be continued during the coming season with a view 

 of determining the amount of arsenic present. 



1 Calculated from daj;a, cited by Nunn, Veterinary Toxicology. 



2 Workers containing little or no feces average about 79 milligrams in weight; on 

 leaving the hive in the morning during the active season the feces may constitute an 

 additional 25 milligrams; a load of honey varies from 22 milligrams to several times 

 that weight. From various references furnished by Dr. B. N. Gates of this Station. 



