. Bulletin of the Department of Agriculture. Agriculture. SACBROOD. 11 colony as a whole, and not in individual bees. Therefore, in describ- ing the symptoms of a bee disease, the colony as a whole should be considered as the unit for description, and not the individual bee. A symptom of disease manifested by an individual bee, broadly con- sidered, is, in fact, also a colony symptom. The symptoms of sacbrood as described m this paper are, therefore, those evidences of disease that are manifested by a colony affected by the disease. It has been found that sacbrood can be produced in a hea
. Bulletin of the Department of Agriculture. Agriculture. SACBROOD. 11 colony as a whole, and not in individual bees. Therefore, in describ- ing the symptoms of a bee disease, the colony as a whole should be considered as the unit for description, and not the individual bee. A symptom of disease manifested by an individual bee, broadly con- sidered, is, in fact, also a colony symptom. The symptoms of sacbrood as described m this paper are, therefore, those evidences of disease that are manifested by a colony affected by the disease. It has been found that sacbrood can be produced in a healthy colony by feeding it a suspension in sirup of crushed larvas dead of the disease. With sacbrood thus produced in ex- perimental colonies the symptoms of the disease have been studied, and the description of these symptoms given here is based chiefly upon observations made in these experimental studies. The facts thus obtained are in accord with those observed in numerous sam- ples of the disease sent by beekeepers from various localities in the United States for diagnosis. They are in ac- cord, furthermore, with the symptoms as they have been observed in colonies in which the disease has appeared, not tlu-ough experimental inoculation but naturally. The symptoms of sacbrood which would ordinarily be observed through a more or less casual examination of the disease will first be considered. It must be remembered that the brood is susceptible to the disease, but that the adult bees are not. SYMPTOMS AS OBSERVED FROM A CASUAL Fig. 7.—Larva dead of sacbrood lying in the cell as viewed from above and at an angle. It may have been dead a month. Cap of cell removed by bees. Enlarged about 8 diameters. (Original.) The presence of dead brood is usually the first symptom observed. An irreg- ularity in the appearance of the brood nest (PI. I, figs. 1 and 2; PL IV) frequently attracts attention early in the examination. The strength of a colony in which the disease is
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