Bee Diseases and Enemies 
401 
has dried down to a scale. Younger unsealed larvse 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 larvae. 
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 
rile it 
it the 
(Fig. 
per- 
dies 
Fig. 107. — European foul brood : a, j, fc, normal sealed cells; b, c, d, e, o, 
i, l, 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 larvse are at¬ 
tacked (Fig. 167, e, m). 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 
trachese may become prominent (Fig. 167, b), giving the 
larvse 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 
