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IV.— THE " SYMPTOMS " OF ACARINE DISEASE. 



Prior to 1920, the presence of this disease in hive bees 

 was recognised mainly by the incapacity of the affected 

 bees for flight, manifested by their crawling upon the 

 ground on leaving the hive. Other associated symptoms, 

 usually present, were also commonly noted, such as 

 retention of faeces and dislocation of wings, but for 

 positive diagnosis, " crawling " in numbers of the adult 

 members of the colony, associated with complete loss 

 of flight power has been the feature relied on as 

 diagnostic of this disease. 



As we now know, " crawling " of the type referred 

 to may be induced by more than one cause, and that 

 under the original and now quite properly discarded 

 designation, " Isle of Wight " disease, were included 

 several maladies having analogous superficial symptoms. 



In the course of now very extensive examinations of 

 diseased bees from all parts of the country I have found 

 that at least 99 per cent, of the stocks reported to me 

 as failed or failing from what has been popularly termed 

 " Isle of Wight " disease harbour the parasite Tarrsone- 

 mus woodi, and the bees showing advanced stages of 

 infestation are obviously in a diseased condition apart 

 from their functional disability as regards flight. The 

 disease of adult bees in this country which is of para- 

 mount importance at the present time is thus the one 

 which is accociated with Tarsonemus woodi. 



In Acarine Disease there are several features of 

 " crawling " deserving special consideration. 



Mass Crawling. 



When the infestation has been multiple in origin, e.g., 

 through robbing, one result that may be anticipated is 

 that the disease will reach a critical stage about the same 

 time in large numbers of bees. This will manifest itself 

 eventually, under certain weather conditions, in a more 

 or less sudden and extensive crawling affecting large 

 numbers of bees. The beekeeper who is unfamiliar with 

 the life history of Tarsonemus woodi looks upon the 

 onset of " crawling " as the commencement of the 



