DIAGNOSING BEE DISEASES IN THE APIARY 15 



ODOR OF DEAD BROOD 



The odors of European foulbrood cannot be accurately described 

 but must be learned by smelling of the dead brood. When there are 

 many decaying larvae in the combs, an odor that is characteristic of 

 this disease can sometimes be detected. Usually the odor of recently 

 dead larvae is slight. A sour odor is sometimes present in partially 

 decayed larvae. Some larvae, particularly those that die after they 

 have straightened out and the cells are sealed, develop a putrid odor 

 resembling the odor of decayed meat. This odor is nearly always 

 present in larvae killed by European foulbrood which in other re- 

 spects resemble larvae killed by American foulbrood. After the 

 odors have been learned, the odor test helps considerably in dis- 

 tinguishing between European and American foulbrood when other 

 symptoms overlap. 



Parafoulbrood 



CAUSE 



Parafoulbrood is caused by bacteria which resemble the bacteria 

 of European foulbrood. Worker, queen, and drone larvae and some- 

 times pupae are killed by the bacteria, which grow within the di- 

 gestive tract, but adult bees are not affected by this disease. The 

 bacterium found in affected brood is known as Bacillus para-alvei, 

 and is present in the spore stage. 



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 progresses 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 others allow it to accumulate. In some apiaries only a few 

 colonies will be diseased, while in others every colony will be affected. 

 Loss caused by parafoulbrood may vary from the weakening of a 

 few colonies to the loss of entire apiaries. This disease usually 

 appears in the spring and disappears by midsummer, but occasionally 

 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 OF THE COMBS 



Infected combs resemble combs with European foulbrood. The 

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



