2 TECHNICAL BULLETIN 14 9, U. S. DEFT. OF AGRICULTURE 



vail within the hive during late winter and spring. The ecology of 

 these fungi on bees in all stages and their relation to bee diseases 

 have never been fully worked out. 



During the past three years a mycological study has been made 

 by the writer, in culture and on bees, of a considerable number of 

 species of fungi that were isolated from adults, larvae, and combs. 

 Experiments have been performed to determine whether the fungi 

 that are commonly found on bees are purely saprophytic or whether, 

 under conditions favorable for infection, they can attack and kill 

 healthy bees or brood. 



HISTORICAL 



The existence of diseases of bees was first recorded by writers be- 

 fore the beginning of the Christian era, but the descriptions are too 

 meager to identify them. The more careful study in Europe of dis- 

 eases of brood dates from the work of Schirach {21) in 1771, but 

 for more than a century following it was quite generally believed that 

 there was only one such disorder. Succeeding reports in Europe sup- 

 ported this view. During the decade just preceding the twentieth 

 century American beekeepers came to believe that more than one 

 . disease of the brood existed, and that these diseases were of decidedly 

 different characters. This has been conclusively proven in the 

 United States, chiefly by the investigations of White, who describes 

 and figures two bacterial brood diseases, a filterable virus . disease, 

 and one protozoan disease of adult bees, in a series of papers dating 

 from 1917 to 1920. The diseases described by him are sacbrood 

 (^5), Nosema disease {29), American foulbrood {30), and Euro- 

 pean foulbrood {31). More recent valuable additions to the knowl- 

 edge of brood diseases and their control have appeared in the publi- 

 cations of Sturtevant {22, 23), and Zander {32, 33). 



The study of diseases of bees due to fungi has been much later in 

 its development than the study of those caused by bacteria. Mucli 

 the greater share of the attention of investigators of bee diseases has 

 been given to the two serious bacterial brood diseases, American foul- 

 brood and European foulbrood, caused respectively by BaxMlws 

 larvae and B. pluton. In America only two -reports are on record 

 of diseases of bees and their brood caused by hyphomycetous fungi. 

 In 1896 Howard {H), of Texas, described a new brood disease which 

 he called " pickled brood or white fungus," caused by a species of 

 Aspergillus to which he gave the name "Aspergillus polUni." Two 

 years later he described {IS) the same disease as occurring in both 

 pupae and adult bees and stated his belief that this disease had been 

 mistakenly diagnosed by beekeepers as paralysis. 



In both reports Howard gives descriptions and illustrations of the 

 disease, which he called " pickled brood or white fungus," which are 

 more readily applicable to the disease known as sacbrood than to 

 those caused by fungi. He ascribed this disease to the pathogenic 

 Aspergillus, A. pollini. The dead larvae are described as at first 

 white and watery, later becoming black and swollen, and finally dry- 

 ing down to black scales. In no case was the fungus, which Howard 

 assumes to be the cause of the disease, observed on the larvae, and 

 isolations of the organism were not made. In adult bees the disease 

 is described as causing black, shiny, apparently frozen abdomens. 



