Bee Diseases and Enemies 



401 



has dried down to a scale. Younger unsealed larvae are 

 sometimes affected. Usually the disease attacks only worker 

 brood, but occasional cases are found in which queen and 

 drone brood are diseased. It is not certain that race of bees, 

 season, or climate have any effect on the virulence of this 

 disease, except that in warmer climates, where the breeding 

 season is prolonged, the rapidity of devastation (Fig. 166) is 

 more marked. Cause, Bacillus larvce. 



European foul brood. 

 This disease (Fig. 167) was formerly called "black brood." 



It usually attacks the larva at an earlier stage of its develop- 

 ment than American 

 foul brood and while it 

 is still curled up at the 

 base of the cell (Fig. 

 167, r). A small per- 

 centage of larvae dies 



Fig. 167. — European foul brood : a, j, k, normal sealed cells ; 6, c, d, e, g, 

 i, I, m, p, g, larvae affected by disease ; r, normal larva at age attacked 

 by disease ; /, h, n, o, dried-down larvae or scales. Twice natural size. 



after capping, but sometimes quite young larvae are at- 

 tacked (Fig. 167, e, to). Sunken and perforated cappings 

 are sometimes observed just as in American foul brood 

 (Fig. 163, c, g, j) . The earliest indication of the disease is a 

 slight yellow or gray discoloration and uneasy movement of 

 the larva in the cell . The larva loses its well-rounded, opaque 

 appearance and becomes slightly translucent, so that the 

 tracheae may become prominent (Fig. 167, b), giving the 

 larvae a clearly segmented appearance. The larva is usually 

 flattened against the base of the cell but may turn so that the 

 ends of the larva are to the rear of the cell (Fig. 167, p) or 

 2d 



