128 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. It 



be considered as the individual unit, as is the case in the majorit}^ of 

 the manipulations of beekeeping practice. This fact makes the problem 

 slightly different from a case of mixed infection as considered from the 

 point of view of human medicine. However, since different individuals 

 are involved in the mixed infections there is no "a priori" reason for 

 considering such cases as impossible. 



The first published report of an authentic instance where both Ameri- 

 can and European foulbrood were found together in the same comb from 

 a diseased colony was reported by McCray.^ This report was concern- 

 ing a sample (4982) received at the laboratory- for diagnosis May 4, 1916, 

 from Stanislaus County, California. Previous to this case only one other 

 such sample (2o9S from Brown County, Wisconsin in 1911) had been 

 received for diagnosis, showing the presence of both diseases, but no 

 report concerning it was published. These two samples were the onl\- 

 known authentic cases on record either in the Bee-Culture Laboratory 

 among practically 5000 samples received up to 1916, or in the beekeeping 

 literature. These two cases were considered to be interesting in that 

 they demonstrated that the presence of both diseases at the same time 

 in a colony was possible, but not much importance was given the matter 

 because of their rare occurrence. White- states that "such a double 

 infection has been encountered in the writer's experience very rarely. 

 In such diagnoses, therefore, after European foulbrood had been found 

 in the sample, American foulbrood is seldom looked for." This practice 

 has been the custom generally as well when American foulbrood was 

 found present in a sample, no further search for European foulbrood 

 being made unless there were present strikingly prominent symptoms 

 abnormal for American foulbrood. As a result the diagnostic records 

 of the Office of Bee-Culture show but six cases of mixed infection up to 

 December 31, 1918, among the approximately 6000 sample records. 



Developments during the year 1919, however, showed that mixed or 

 double infection is more probable than had been previously supposed. 

 These facts were particularly impressed upon the writer during the 

 spring of 1919 while on a trip investigating the bee disease conditions in 

 the State of California. While in the field during a period of less than 

 one month, and in three different counties of the State of California, six 

 cases were found showing both American foulbrood and European foul- 

 brood in the same colonies. Each case was diagnosed posivitely at 

 once in the field by means of microscopic examination of dead larvae 

 showing characteristic s^Tnptoms of the two diseases and found to con- 

 tain the specific causative organisms. It is interesting to note that three 



^McCray, A. H. 1916. Report of the finding of American Foulbrood and European 

 foulbrood in the same comb. Jour, of Eco. Ent. Vol. IX, p. 379. 



^White, G. P., 1920. European foulbrood. U. S. Dept. of Agric. Bui. 810. 



