DIAGNOSING BEE DISEASES IN THE APIARY 31 



FUNGOUS DISEASES OF ADULT BEES 

 CAUSES 



It has been known for many years that in Europe a disease of 

 adult honeybees is caused by a common fungus, Aspergillus -flavus. 

 In North America it has recently been found that this same fungus 

 and several others attack adult bees. A. -flavus has already been 

 noted as attacking brood (p. 23). When recently emerged bees are 

 kept at a temperature about 12° or 14° below that of the brood 

 nest they may be attacked and killed by Mucor Memalis, a fungus 

 closely related to the common black bread mold. Old bees are not 

 affected by this fungus. 



Spores of pathogenic fungi get into the digestive tract of bees 

 with food or with water. If a bee comes in contact with fungus 

 spores, some of them may. cling to the mouth parts and be swal- 

 lowed later. Nonpathogenic fungi are unable to grow within the 

 stomach of bees, and the fungi themselves may be killed. Patho- 

 genic fungi, on the other hand, grow readily. At first the fungus 

 grows within the stomach, but later the muscles and other soft tis- 

 sues are penetrated by numerous fungus branches, and death re- 

 sults. When dead bees are kept under moist conditions, the fungus 

 may grow through the body wall and form spores on the outer 

 surface (fig. 20). 



Figure 20. — Adult workers and a drone bee killed by Aspergillus flavus. Spores of the 

 fungus are seen on tbe bodies of tbe bees. 



IMPORTANCE 



Losses of adult bees caused by fungi are usually of little economic 

 importance. When pathogenic fungi grow within the hive on combs, 

 frames, dead bees, etc., late in the winter or early in spring, fungous 

 diseases are most likely to cause significant losses. This can be 



