DIAGNOSING BEE DISEASES IN THE APIARY 21 



APPEARANCE OF THE DEAD BROOD 



A larva killed by a fungus becomes noticeably harder soon after 

 it dies, and the glistening white changes to a dull creamy white. 

 Later the dead larva becomes shrunken and wrinkled. The head 

 end of a larva that dies after it has straightened out in the cell dries 

 most rapidly and often curves upward at first but later tends to 

 straighten out again. The fungus soon grows through the skin in a 

 ring just back of the head and forms a sort of white collar. Within 

 1 to 2 days the fungus grows over the entire larva and forms a false 

 skin which clings closely to the true skin. The color at this stage is 

 chalky white. The fungus produces spores on the outer surface of the 

 dead larva, and the white changes to a shade of green, black, or other 

 color, corresponding to the color of the spores. Spores form earliest 

 and most abundantly near the head end of dead larvae. The color of 

 the spores deepens as they mature and fades as they become old and 

 dry. After dead larvae and pupae have become dry they are known 

 as mummies. In Europe the disease of bees caused by Aspergillus 

 flavus is called "stone brood" on account of the hard texture of the 

 dead brood. 



DISEASES OF ADULT BEES 



What to Observe When Looking for Diseases of Adult Bees 



No general rules can be given for the diagnosis of diseases of adult 

 bees. Such diagnosis is made more difficult by the fact that at any 

 time of the year many bees may die as a result of old age or abnormal 

 conditions. Symptoms of the different diseases overlap, and usually 

 a diagnosis cannot be made in the apiary. There are a few dependable 

 symptoms of diseases of adult bees, however, which can be recognized 

 without a miscroscope, and with good samples it is sometimes possible 

 to make a diagnosis in the apiary. 



Nosema Disease 

 cause 



Nosema disease is caused by a minute, single-celled animal parasite 

 known as Nosema apis. Adult workers, drones, and queens are af- 

 fected. Spores of N. apis enter the body of the adult bee with food 

 or water. They germinate within the stomach and attack the tissues 

 which line the stomach or mid-intestine, with varying harmful effects. 



importance 



Nosema disease is widespread and, under conditions favorable to it, 

 causes extensive losses of adult bees. It has also recently been shown 

 to be responsible, to a degree heretofore unsuspected, fo rthe super- 

 sedure of queens in colonies established from infected package bees. 

 When accompanied by dysentery brought on by long winter confine- 

 ment, the disease may spread rapidly within infected colonies and re- 

 sult in the death of the colonies late in the winter or in the spring ; or 

 heavy losses from Nosema disease may continue for weeks after the 



