February, "21] sturtevant: mixed infections 131 



Table IV. — Distribution of Samples of Mixed Infection by Months 



April o 



May 9 



June 10 



July 1 



August 6 



September 5 



October 1 



November 1 



These samples of mixed infection have been examined in eight out of 

 the twelve months of the year, April to November inclusive, as shown in 

 Table IV. Twefity-four of the total 38 samples, nearly 65 per cent., 

 were examined during the months of April, May and June, the months 

 during which European foulbrood is most prevalent.^ In contrast to 

 the spring months, eleven samples of mixed infection were examined 

 during August and September, and only one each in July, October and 

 November, a total of fourteen. 



The question, however, of which diesase is most often the primary 

 invader in a colony is difficult to answer, particularly without a history 

 of the colony and locality. (Table I) . If only dried adhesive American 

 foulbrood scales are found, accompanied by numerous coiled fresh moist 

 melting larvae of European foulbrood, it is not difficult to say that 

 American foulbrood was the primary invader, perhaps during the pre- 

 vious season, as was the case of the sample reported by McCray. But 

 often there is no such demarkation. Because the presence of American 

 foulbrood depletes the strength of the colony this increases the probabil- 

 ity of European foulbrood infection. 



Since the requirements of the treatment of the two diseases are so 

 entirely different, the necessity for correct diagnosis becomes of im- 

 portance, particularly in regions where both diseases have been prevalent 

 for some time. The presence of both diseases in the same colonies or 

 even in the same apiary is a complicating factor in the diagnosis and 

 treatment. Furthermore there is danger from the possibility of con- 

 tinued and confusing losses due to the ignorance of the presence of mixed 

 infection in colonies under such circtmistances and resulting therefrom, 

 improper treatment which would only continue the losses. 



Several samples have been received for diagnosis which beekeepers 

 have thought contained both diseases and which indeed seemed to have 

 some of the characteristics of each. Upon careful examination, however, 

 both gross and microscopic, these have mostly proven to be definitely 

 not mixed infections. The recognition of cases of mixed infection in 



•^Phillips, E. P.. H»18. Tlie control of European foull^rood. U. S. Dept. of Agnc. 

 Farmers' Bulletin 975, IG pp. 



