6 BULLETIN 809, U. S. DEPARTMENT OF AGRICULTURE. 



however, they are altered, being sometimes punctured (PI. Ill, A; 

 PI. VI, C), sometimes sunken, and sometimes darkened. Sometimes 

 these abnormal appearances are combined. The holes in the caps 

 vary in number and dimensions. Ordinarily there is but one (PI. Ill, 

 A), although there may be two (PI. VI, C) or more. They are usually 

 the size of a pinhead or smaller. The puncturing of the caps is done 

 by the adult bees, and at the time of observation any proportion 

 of the cap may have been removed. 



Sunken caps are found only after the disease has been present in 

 the colony for a considerable period, weeks at least. This symptom 

 is most marked after the brood frames have been roughly handled, 

 as in shaking bees from them or shipping them by express or mail 

 (PI. I, C). This condition of the caps is encountered more fre- 

 quently in samples shipped to the laboratory than in those taken 

 directly from the affected colony. By rough handling the viscid 

 decaying mass within the cell is brought in contact with the cap, 

 adheres to it and tends to draw the cap inward as it settles, accounting 

 in a large measure for the condition referred to as sunken cappings. 

 The dark caps occur somewhat later and also depend largely upon 

 the presence of decaying brood material within the cell. The caps 

 of many cells containing dead brood, however, are neither sunken 

 nor darkened by its presence. 



When recently dead the decaying brood in American foulbrood 

 is light brown in color, the shade deepening as the process of decay 

 continues. The color passes through a chocolate, coffee, and mahog- 

 any brown, reaching a very dark shade as it approaches the scale stage. 



The body wall of a larva or pupa dead of the disease soon softens 

 and is easily ruptured, making it impossible to remove the remains 

 intact from the cell. As the process of decay continues the mass 

 becomes viscid and before the scale stage is reached the viscidity is 

 such that it is capable of being roped out into fine threads to a dis- 

 tance of 2 or 3 inches and sometimes even more. The scale when 

 dry adheres more or less firmly to the cell wall. 



The odor of the brood combs, when it is present, is character- 

 istic of the disease and may be spoken of conveniently as the foul- 

 brood odor. It is never detected in the early stages of the disease 

 and if only scattering cells are present seldom is noticed. When 

 much brood is d}ung and the disease has been present for weeks, 

 the odor is noticeable and sooner or later becomes marked. When 

 marked it is recognized by its strong and penetrating character and 

 is usually thought of as being disagreeable. The brood combs 

 after their removal from the hive tend to lose this foulbrood odor. 

 The presence and extent of it in samples of the disease vary con- 

 siderably, the variation depending largely upon thft facts just 

 mentioned. 



