DIAGNOSIS OF BEE DISEASES. 5 



the caps usually are entire, but may be punctured. The caps may be 

 slightty sunken, but usually are not. Owing to the fact that such 

 a small percentage of the affected brood becomes sealed, a comb of 

 brood affected with European foulbrood with its few sealed cells and 

 large amount of young uncapped brood presents a distinctive appear- 

 ance (PL I, fig. 1) and shows a marked contrast to the solid areas 

 of brood of uniform age in healthy combs. 



(b) Proportion of affected brood. — European foulbrood usually 

 has made rather extensive ravages by the time the beekeeper detects 

 it; hence in many samples received for diagnosis a very large pro- 

 portion of the larvae in the comb are affected. Toward autumn, 

 however, it is not unusual to receive samples containing a small num- 

 ber of affected larvae. 



(c) Position of larvae within the cell. — The usual position for 

 larvae affected with European foulbrood is that of lying curled at the 

 bottom of the cell. Other affected larvae lie extended in the cell, 

 but these are few in number. 



(d) Age of the dead larvm. — In most of the specimens received 

 for diagnosis by far the larger proportion of the affected larvae are 

 young, lying curled at the bottom of the cell as just stated. Besides 

 this comparatively young brood, older larvae, including a few sealed 

 ones, may be found affected. 



(e) Color. — A change in color is one of the first abnormalities 

 noted in brood dead of European foulbrood. Yellow or gray and 

 combinations of these two colors are among the first to be noted. 

 Later the } T ellow and gray gradually deepen, until quite a dark brown 

 is attained. Larvae dead of this disease often present a peculiar 

 appearance, as though they were melting away under the influence of 

 heat. The transverse tracheal branches stand out prominently. This 

 melting appearance of the larvae, the yellow, gray, and brown colora- 

 tion, prominent tracheal branches, and large amount of uncapped 

 affected brood are characteristics not easily confused, in the majority 

 of cases, with those of other diseased conditions of the brood. 



(/) Consistency. — Larvae dead of European foulbrood are com- 

 paratively friable. However, larvae which are somewhat viscid usu- 

 ally may be found. Perhaps slimy, rather than viscid, expresses 

 better the consistency of some of these larvae. 



(g) Odor. — A slight, inoffensive odor is frequently to be noted in 

 European foulbrood. The yeastlike odor which has been described 

 is not constant in brood affected with European foulbrood. A simi- 

 lar odor may be detected in samples other than those which contain 

 European foulbrood. 



(/?,) Kind of brood affected. — Sometimes samples are received 

 which contain only affected drone-brood. Most cases, however, con- 

 sist only of worker-brood. Queen larvae also may be attacked. 



