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 larva. 
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 ; b, c, d, e, g. 
i, l, m, p, q, larva affected by disease ; r, normal larva at age attacked 
by disease; f, h, n, o, dried-down larvse or scales. Twice natural size. 
after capping, but sometimes quite young larvae are atr 
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 
trachea? may become prominent (Fig. 167, 6), 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 
2 D 
