33 



from Isle of Wight disease. But as bees may also die during 

 winter from purely natural causes, it becomes important, from 

 the point of view of the well-being of the apiary, to determine 

 to what particular agency, the death of a colony has been due. 



In the absence of disease, the extinction of a colony in winter 

 may be due either to loss of queen or to lack of food. In the 

 former case, there will be few, if any, worker bees left alive in 

 the spring : the colony will have perished owing to there being 

 no births to compensate the deaths. On the other hand, a 

 diminution of a colony through lack of food is evidenced by 

 the dead bees clustered on the combs, many with their heads 

 inside the cells. Some of them may be noticed with their 

 tongues extended. The cells will be empty of honey and sugar 

 syrup, but there will be brood in various stages if the bees 

 were alive until the end of January. In neither of these cases 

 i? there any soiling of the combs, and there is no objectionable 

 odour. 



If, however, the death of the colony has been due to the Isle 

 of Wight disease, the dead bees will be found scattered over 

 the combs and on the floor of the hive; there will be abundant 

 supplies of food and also a small batch of brood, showing that 

 the queen performed her duties up to the last. But the combs 

 and also the interior of the hive will be soiled with the excreta 

 of the bees. There is" a further important distinction in the 

 bodies of bees which have died from natural causes and those 

 which have perished from Isle of Wight disease. Normally 

 the bodies of dead bees shrivel up soon after death, and the 

 abdominal contents will be found to be perfectly dry. But 

 in the case of death due to Isle of Wight disease the intestine 

 is filled with a fluid which gives off a very foul odour. 

 Provided that the body wall is not ruptured, we have found 

 that the intestinal contents will retain their fluid condition 

 .for a period of six months. On exposure to air, however, 

 this liquid mass quickly becomes solid. 



Infection Experiments. 

 To illustrate the facility with which the disease can be 



