EXPERIMENT iSTATION BULLIBTINS. i;03 



necessary for the bees to make the combs free from scales. However, it is 

 not necessary to wait mitil the diseased combs are completely clean as the 

 introduction of a young laying queen sometimes stimulates the bees to greater 

 activity in cleaning house, and although a few cells of disease may appear 

 after the queen has been introduced it will soon disappear completely. 



It is extremely desirable to treat at the beginning of or during a honey 

 flow, as the incoming nectar and the hive activity associated with a honey 

 flow stimulates the young bees to greater activity in the removal of diseased 

 material and greatly assists in the success of the treatment. It is very neces- 

 sary^ to have the colonies as strong as possible during the queenless period 

 and full of young bees. It is not considered necessary to disinfect hives 

 which have contained European foul-brood before using for healthy colonies. 

 Combs which are so foul that it is not advisable to compel bees to clean them 

 should be treated as American foul-brood combs. 



Sac-Brood. 



Sac-brood is an infectious disease of bees in the brood stage, the cause of 

 which has been proved to be a filterable virus. Its effect upon the colony 

 is usually not serious. Due to the fact that larvae die of sac-brood at ap- 

 proximately the same time as those attacked by American foul-brood a 

 careless observer might, at first glance, mistake sac-brood for American. 

 However, the position of the scale in the cell, well compared to the shajDe of 

 a Chinaman's shoe, together with the looseness of the scale in the cell makes 

 differentiation simple. 



The method of spread of the virus is not well known, nor is the relation 

 of the race of bees to resistance to the disease of value. In ordinary beekeep- 

 ing practice, a treatment for sac-brood is rarely necessary. Requeening a 

 colony which has a severe attack, with a vigorous 3' oung laying queen usually 

 cleans up the disease. The virus is not present in the scales, and a hive 

 which has contained a colony suffering from sac-brood should be all right for 

 use with a healthy colony without treatment. 



Is'osEMA Disease. 



Nosema disease is a disease of adult bees caused by the protozoan No§ema 

 apis. It is probable that the disorder caused by Nosema apis is recognized 

 by other names in different countries and in different sections of the United 

 States. It is not known that there is any relation between Nosema disease 

 and Isle of Wight disease, and there probably is not. The disease attacks 

 the adult bees through the alimentary tract. Usually the first symptoms 

 of nosema disease is weakness of the colony. As the affected bees behave 

 similar to healthy ones, a slight attack on the colonj^ would never be noticed. 

 The disease does not affect the brood, and work in the colony goes on nat- 

 •urally. The method of spread of the disease is not well known. The spores 

 of the disease pass out of the affected bee in the excrement. Should this 

 excrement fall in the water supply of the bees it would furnish one means of 

 spread. The bodies of bees dead from nosema. disease in the water supply 

 would probably transmit the disease. The infection may or may. not kill 

 the colony. It does, however, weaken the colony to such an extent that in 

 many cases little or no surplus honey is stored. As diseased colonies become 

 weak it is probable that robbing is one means of spread of the disease. • The 

 (iise^ase is pot considered of great importance iii Michigan at present. 



