—_—, G3a-673 Issued January 15, 1913. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY—CIRCULAR No. 169. L. O. HOWARD, Entomoleest ead Chief of Berean, SACBROOD, A DISEASE OF BEES. BY G. F. WHITE, M. D., Px. D., Expert in Bacteriology. WASHINGT ON = GOVERNMENT FSINTING CFFAICE = tots . BUREAU OF ENTOMOLOGY. L. O. Howarp, Entomologist and Chief of Bureau. C. L. Martart, Entomologist and Acting Chief in Absence of Chief. R. S. Currron, Hxrecutive Assistant. W. F. Tastet, Chief Clerk. F. H. Currrenbden, in charge of truck crop and stored product insect investigations. A. D. Horxins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations. I’. M. WEBsTER, in charge of cereal and forage insect investigations. A. L. QUAINTANCE, in charge of decidwous fruit insect investigations. EB. F. Puitiies, in charge of bee culture. D. M. Rocers, in charge of preventing spread of moths, field work. Rorta P. Currikz, in charge of editorial work. MapBet Coxucorp, in charge of library. INVESTIGATIONS IN BEE CULTURE. BE. F. PHruires, in charge. G. F. WuiITsE, J. A. NELSON, experts. G. S. DemutTH, A. H. McCray, N. E. McInboo, apicultural assistants. D. B. CASTEEL, collaborator. PEARLE H. GARRISON, preparator, II CIRCULAR No. 169. Issued January 15, 1913. United States Department of Agriculture, BUREAU OF ENTOMOLOGY. L. O. HOWARD, Entomologist and Chief of Bureau. SACBROOD,' A DISEASE OF BEES. By G. F. Wuitsr, M. D., Ph. D., Expert in Bacteriology. INTRODUCTION. The purpose of this preliminary paper is to discuss briefly a dis- ease, which has been recognized by the bee keepers for many years as dead brood, that is different from foul brood. Sacbrood, therefore, is no new disease. Samples of it have been received from all the States except three, together with samples from Canada. This disease really has had no name. In recent years many bee keepers have by mistake spoken of it as “ pickled brood.” The pickled brood as William R. Howard describes it, however, is a very different disease. Before considering sacbrood it. might be well to explain briefly what is meant by pickled brood. PICKLED BROOD. In 1896 William R. Howard, of Texas, wrote a paper in which he describes a disease of bees that he calls “ pickled brood.” He de- clared in his paper that the disease was caused by a fungus to which he gave the name Aspergillus pollinit. In 1898 he wrote a second paper in which he says that the fungus may attack not only the larvee and pupe but adult bees as well. Maassen in 1906 mentioned a disease of bees which he says is caused by a fungus stated by him to be similar to Aspergillus flavus and easily isolated from the larve, pups, and adult bees affected by the disease. These two men, then, Howard and Maassen, have each written of a disease of bees which they believe to be caused by a fungus. By each it is claimed that the fungus can attack adult bees as well as the larve and pupe. Howard named the disease which he mentioned “pickled brood,” and Maassen referred to the disease which at- 1 This circular will be followed by a bulletin of this bureau in which this disease will be treated more fully. 1 2 SACBROOD, A DISEASE OF BEES. tracted his attention as an “ aspergillusmycosis in bees.” The dis- eases, as described by Howard and Maassen, then, would be called fungous diseases. If there are any such fungous diseases of bees in the United States they have not yet attracted the attention of the bee keepers. I base this conclusion upon the fact that during my study of bee diseases there has not yet been received from the bee keepers any sample that could be considered a fungous disease. If future investigations demonstrate that there exists a fungous disease like the one Howard has described, then the name “ pickled brood ” can be used to desig- nate it. When using the term “ pickled brood” in the future the possible disease condition described by Howard will be meant. A DISEASE OF THE BROOD WHICH IS NOT FOUL BROOD. There is a disease of the brood of bees that has attracted consid- erable attention among bee keepers that is neither American foul brood, European foul brood, pickled brood, chilled brood, nor starved brood. This disorder of the brood has for many years been recognized by bee keepers as being different from foul brood. Doo- little, of America, in 1881 wrote of a disease which he says is similar to and called foul brood but which is not foul brood. He writes that the larvee die here and there throughout the brood comb and that the disease may disappear entirely or it may reappear the next sea- son. Jones, of Canada, in 1883 wrote also of a disease which results in a dying of the brood, with appearances similar to foul brood; but he states that the disease is*not foul brood. He says that the bees frequently remove the dead brood and that no further trouble ensues. Simmins, of England, in 1887 wrote of dead brood which he says is not foul brood, and describes the difference in appearance between the brood dead of the disease and brood dead of foul brood. He states, furthermore, that the condition is different from chilled brood and that Cheshire did not find any microscopic evidence of disease in larve dead of the disease. An editorial in one of the bee journals in 1892 is of particular interest at this point. The editor wrote that he had recently encountered dead brood which did not seem to be infectious and which lacked two decisive symptoms of the real foul brood, viz, the ropiness and the glue-pot odor. My own study of this dead brood, recognized by the bee keepers as being different from foul brood, was begun in 1902. Eight sam- ples labeled “ pickled brood ” were received from the bee inspectors of New York State during 1902 and 1903. These samples were ex- amined and were found to be practically free from microorganisms. The results of these examinations were published in January, 1904. Burri, of Switzerland, in 1906 reported the results of the examination of 25 samples of brood material thought by the bee keepers to be SACBROOD, A DISEASE OF BEES. 3 diseased. He placed the results of his examinations under the follow- ing headings: “Sour brood,” “stinking foul brood,” “nonstinking foul brood,” and “dead brood free from bacteria.” Four of the 25 samples examined contained dead brood free from bacteria and unac- companied by other diseases. Kiirsteiner, of Switzerland, in 1910, in classifying the results obtained from samples examined by him, made the same classification as made by Burri. During the past six years 326 samples of this disease have been received by the Bureau of Entomology and diagnosed in its bacteriological laboratory. There is, therefore, a disorder attacking the brood of bees in which brood dies, but in which there has not been demonstrated any micro- organism to which the cause of the trouble could be attributed. For this disease the name of “ sacbrood ” is here suggested. THE NAME SACBROOD. As stated, my first examination of this dead brood was made in 1902, when samples were received diagnosed by bee keepers as “pickled brood.” The fact was easily determined at that time that the disease could not be considered a fungous disease and was there- fore not pickled brood. In the past my preference has been to refer to this condition only as the “so-called pickled brood.” Since the disease is not pickled brood, it will produce less confusion and be more scientific if the term “ pickled brood” be entirely omitted in the name for the disease. Many larvae dead of this disease can be removed from the cell without rupturing their body wall. When thus removed they have the appearance of a small closed sac. This character suggested the name “ sacbrood.” The name has the virtue, therefore. of being both appropriate and brief. THE SYMPTOMS OF SACBROOD. The strength of a colony in which sacbrood is present is frequently not noticeably diminished. When the brood is badly infected, how- ever, the colony naturally becomes appreciably weakened thereby. The brood dies after the time of capping. The dead larve are there- fore almost always found extended lengthwise in the cell and lying with the dorsal side against the lower wall. It is not unusual to find many larve dead of this disease in uncapped cells. Such brood, however, had been uncapped by the bees after it died. In this disease the cappings are frequently punctured by the bees. Occasionally a capping has a hole through it, indicating that the capping itself had never been completed.