20 



BULLETIJT 804, U. S. DEPARTMENT OF AGRICULTURE 



eased colony, more discolored larva3 appeared, showing definitely the 

 'development of the disease. As far as could be seen the only source 

 of infection was the queen which had come from a diseased colony. 



This occurrence had been observed previously by the author while 

 employed at the Massachusetts Agricultural Experiment Station. 

 During the summer of 1916 eight queens taken from diseased Euro- 

 pean f oulbrood colonies were introduced into isolated, healthy nucleus 

 colonies. Of these eight nuclei three developed European f oulbrood, 

 two were doubtful, and three remained healthy. Several such in- 

 stances have been mentioned in the literature of beekeeping. 





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Fig. 6. — Distribution of cells containing infected sugar sirup and subsequent spread 



of the disease in a comb taken from colony H Area covered 



by brood at time of infection, mostly unsealed. • Location of cells con- 

 taining infected colored sugar sirup on July 3, 1918. First i>ositive diseased 

 larvae noted, 2 on July 8. © Number of ne-^^ diseased larvaj (4) on July 10. 

 A Number of diseased larvaa (13) on July 12. D Number of diseased larvse (39) 

 on July 16. O Number of diseased larvse (52) on July 19. 



DISTRIBUTION OF INTRODUCED INFECTED MATERIAL 



An interesting experiment was carried out with sugar sirup, colored 

 by a small amount of a harmless anilin dj^e, eosin, used as an indi- 

 cator, which gave to the sirup a bright red color. The object of this 

 experiment was to determine where the sirup, or, more important, 

 where fresh nectar is first placed in the hive and combs. On May 27 

 two colonies were fed this colored sirup from above some time before 

 the heav}^ honey flow from clover started. The results were striking, 

 for in nearly every case the colored sirup was easily discernible in the 

 cells and the greatest part of the sirup was located in quite a definite 

 area. These colored cells were either scattered among the ceils con- 

 taining the larvae or were placed in a ring of cells adjacent to the 

 brood area toward the top of the comb, little being placed with the 

 solid stores (fig. 6). Furthermore, for nearly 36 hours after the 

 feeding practically all the young nurse bees showed a marked pinkish 

 discoloration of the anterior end of their abdomens, denoting the dis- 



