NOSEMA-DISEASE. 21 



in the spring. Some colonies died as a result of the disease, while 

 a greater number recovered from the infection, increased in strength, 

 and behaved in all respects as healthy colonies. 



The total of all the spring counts, during the period from 1912 

 to 1915, inclusive, of the apiary under study, was 94 colonies. Out 

 of this number at least 12 (13 per cent) died more or less directly 

 as the result of Ndsema disease. An equal or greater loss to the 

 apiary than this colony loss probably is the aggregate loss in strength 

 sustained by colonies weakened by the infection but which recover 

 from the disease. 



Naturally it is particularly unfortunate from an economic point of 

 view that the highest percentage of infected bees, and consequently 

 the heaviest loss in strength sustained by colonies from Nosema 

 infection, occurs in the spring. 



Beuhne (1916) has reported investigations made on colonies from 

 his own apiary which are similar in nature to the foregoing studies. 

 The results he obtained indicate that Nosema infection in Australia 

 is similar to the infection as it occurs in America. 



SYMPTOMS OF NOSEMA-DISEASE. 



Nosema-disease presents only a few symptoms. In describing 

 them the colony rather than individual bees should be considered as 

 the unit, since it is the colony as a whole that is of primary interest 

 to beekeepers. 



Weakness is a colony symptom which invariably will be manifest if a 

 sufficiently large percentage of the bees of the colony are Nosema in- 

 fected and if the infection persists for a sufficient period. When only a 

 small percentage of the bees are infected the weakness resulting may 

 never be apparent. The loss in strength may be gradual or sudden. 



The behavior of a Nosema-infected colony is similar to that of a 

 healthy one. The stores are sufficient. The queen does her work 

 well. As the colony dwindles the queen usually is among the last 

 handful of bees. The brood in general is normal in appearance, but 

 in colonies weakened by the disease not infrequently it is seemingly 

 in excess of the amount that can be properly cared for by the adult 

 bees present. 



In Nosema-disease the workers especially suffer from the infection. 

 An infected bee manifests no outward symptoms of the disease when 

 seen among the other bees of the colony and it performs functions 

 similar to those performed by healthy ones. 



When the stomach of an infected bee is removed it may show 

 marked changes which are characteristic of Nosema-disease. The 

 organ pales as a result of infection. The brownish yeUow or dark 

 reddish hue of the normal stomach is gradually lost as the disease 

 advances. The organ (PI. I) is often increased in size, the circular 



