28 CIRCULAR 3 92, U. S. DEPARTMENT OF AGRICULTURE 



IMPORTANCE 



Very little is known about the disease, but the infected bees are 

 undoubtedly injured. Its economic importance is probably negligible, 

 although this point has not been definitely determined. 



SYMPTOMS 



The disease cannot be recognized in the apiary by any symptoms. 

 Dead bees that contain the parasites do not differ in appearance from 

 bees dead of other causes. Field bees that appear entirely normal 

 may also be infected. The parasites are found, often in large num- 

 bers, in the excretory organs (nialpighian tubules) of the bees. 



Fungus 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 fungus and 

 several others attack adult bees. A. flaws has already been noted 

 as attacking brood (p. 20). When recently emerged bees are kept 

 at a temperature about 12° or 14° F. below that of the brood nest, 

 they may be attacked and killed by 31 v cor hiemalis, 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 conies 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. 



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, fungus 

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

 largely prevented, however, by providing good wintering conditions 

 for the bees. 



SYMPTOMS 



The first noticeable symptoms are restlessness and weakness. 

 Weakness increases until death occurs. A few sick bees may die 

 in or near the hive, but they usually fly or crawl from the hive and 

 seem intent upon getting as far away as possible before they die. For 

 this reason mycosis of adult bees is likely to be overlooked, particu- 

 larly when only a few bees at a time are affected. 



