SACBROOD. 



13 



"scale'- (figs. 22, 23; PI. II, I, r, and x). This scale is not adherent 

 to the cell wall. 



In sacbrood the brood combs may be said to have no odor. Larvae 

 undergoing later stages of decay in the disease, however, when 

 crushed in a mass and held close to 

 the nostrils are found to possess a 

 disagreeable odor. 



From a superficial or casual ex- 

 amination alone of a case of sac- 

 brood it may be mistaken for some 

 other abnormal condition of the 

 brood. A careful study of the post- 

 mortem appearances of larva? dead 

 of the disease, however, will make it 

 possible to avoid any such confusion. 

 A more careful study of the dead 

 larvae is therefore justified. 



Fig. 10.— Cap of cell containing the remains 

 of a larva dead of sacbrood. The cap is 

 slightly sunken and bears two perforations 

 made by the bees. (Original.) 



APPEARANCE OF LARV^ DEAD OF SACBROOD. 



No signs in a larva dying of sac- 

 brood have yet been discovered by 

 which the exact time of death may be determined. As the larvae in 

 this disease usually die during the time when they are motionless, lack 



of movement can not be used as an 

 early sign of death. In this descrip- 

 tion it is assumed that the larva is 

 dead if it shows a change in color 

 from bluish-white to yellowish or 

 indications of a change from the 

 normal turgidity to a condition of 

 flaccidity. 



I lIl^^^R^t' iP'i The a pp earance ° f a iarva dead 



#/ ^ot,^\#X.^- J/A. ,/A of sacbrood varies from day to day, 



changing gradually from that of a 

 living healthy larva to that of the 

 dried residue — the scale. A de- 

 scription that would be correct for 

 a dead larva on one day, there- 

 fore, may and probably would be 

 incorrect for the same larva on the following day. Moreover, all 

 larvae dead of the disease do not undergo the same change in appear- 

 ance, causing another considerable range of variation. For con- 

 venience of description, this gradual and continual change in appear- 

 ance is here considered in five more or less arbitrary stages. As the 



Fig. 11.— End view of cell containing a larva 

 dead of sacbrood, with a cap which has the 

 appearance of never having been com- 

 pleted. (Original.) 



