THE DISEASES OF BEES. 89 



wherever it appeared. So terrible is this scourge that an 

 authority as painstaking and eminent as Mr. T. W. Cowan 

 tells us in the British Bee Journal for March 4th, 1920, that, 

 from carefully compiled statistics, it has been proved that 

 about 90 per cent, of the colonies of bees that existed in 

 Somersetshire had been destroyed by this disease; and much 

 the same has happened in every other county. 



The origin of this disease is still very obscure. For long 

 it was thought that it was caused by the existence in large 

 numbers in the bee's chyle, stomach, or intestine of tiny 

 microscopic animal parasites or protozoans known as Kosema 

 apis ; but, as this protozoan is also found to be present in 

 other diseases of bees, which have nothing to do with 

 Isle of Wight disease, it became doubtful whether it was 

 really the root cause of this disease. A great deal of careful 

 research work has since been carried out both by inde- 

 pendent men of science and by the Government. Drs. Rennie 

 and Wood state * that it is caused by a parasitic organism 

 of the Acharea family (which they have named Tarsonemns 

 Woodi) invading the respiratory organs. 



Symptoms of Isle of Wight Disease. 



In the early stages of the disease the bee-keeper will notice 

 that many of the bees, as they issue from the hive entrance, 

 are unable to fly. Tliey wander listlessly about the alighting- 

 board, falling off it after a time, and then crawl about the 

 ground and on blades of grass, etc. As evening approaches, 

 they generally collect in clusters for warmth, but soon become 

 chilled through in the night and die. These bees are known 

 as " crawlers." 



On the other hand, other of the bees that are affected by 

 this disease dart quickly from the entrance and succeed in 

 flying a considerable distance from the hive. 



With reference to " crawlers," afflicted with Isle of Wight 

 disease, the bee-keeper must be particularly careful not to 

 confuse bees which, in perfectly healthy hives, returning heavily 

 laden from the fields, sometimes miss the alighting -board 

 (especially in windy weather), and falling to the ground, crawl 

 about for a while, being too tired to rise again at the moment. 



* "Isle of Wight Disease in Hive Bees," by John Rennie, "D.Sc, P. B. White, B.Sc., 

 and Elsie J. Harvey, published by R. Grant & Son, Edinburgh, price 9s. 



