SACBKOOD. 



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 in 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 larvae 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 

 through 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 

 EXAMINATION. 



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 (PL I, figs. 1 and 2; PL IV) frequently attracts attention early 

 in the examination. The strength of a colony in which the disease 

 is present is often not noticeably diminished. Should a large 

 amount of the brood become affected, however, the colony 

 naturally becomes weakened thereby, the loss in strength soon 

 becoming appreciable. Brood that dies of the disease does so 

 almost invariably in capped cells, but before the pupal 



