16 CIRCULAR 3 9 2, U. S. DEPARTMENT OF AGRICULTURE 



DISTRIBUTION AND RACES OF BEES AFFECTED 



This disease has been found only in limited sections of North Caro- 

 lina, South Carolina, Georgia, and Florida. All the races of bees 

 common in North America are susceptible, but Italians appear to be 

 more resistant than are common blacks and hybrids. Weak colo- 

 nies are usually more seriously affected than strong ones, but heavy 

 losses of brood may also occur in strong colonies. 



EFFECT UPON COLONIES 



Parafoulbrood progi'esses rapidly within some colonies and se- 

 riously weakens or kills them. In others it progresses slowly, the 

 colonies are not noticeably weakened, and the disease disappears of 

 its own accord. Some colonies clean out the dead brood promptly, 

 while in others it is allowed to accumulate. In some apiaries only 

 a few colonies will be diseased, while in others every colony will be 





Figure 11. — Parafoulbrood ; a heavily infected comb showing larvae in various stages of 

 disease and decay after death. 



affected. Loss caused by parafoulbrood may vary from the weak- 

 ening of a few colonies to the loss of entire' apiaries. This disease 

 usually appears in the spring and disappears by midsummer, but oc- 

 casionally colonies exhibit symptoms of the disease throughout the 

 year, or there may be a slight increase of infection in the autumn. 

 The first brood reared in the spring is not affected. 



SYMPTOMS 

 APPEARANCE OP THE COMB.S 



Infected combs resemble combs with European foulbrood. The 

 brood is more or less irregular, depending upon the amount of 

 infection and the length of time the disease has been active (fig. 11). 



