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VI.— DIAGNOSIS AND GRADING OF ACARINE 

 INFESTATION. 



Examination of Bees for Diagnosis. 



The following advice is offered to the increasing 

 number of expert beekeepers and microscopists who are 

 now undertaking the examination of bees for Acarine 

 Disease. 



I. The taking of the sample. For a prognosis regard- 

 ing any stock of bees suspected of disease, the sample 

 should be as large as possible and consist of live bees 

 taken at random off the frames. Samples which are 

 made up of disabled bees (" crawlers ") alone are not 

 satisfactory for this purpose, since if the disability is 

 due to acarine disease, these may be expected to show 

 a hundred per cent, infestation. Such samples are 

 useful only in indicating the presence or absence of 

 this disease, 



II. In the sample taken as directed above, the pro- 

 portion of clean and infested bees should be determined 

 by examination of the bees individually. The larger 

 the sample the more reliable is the result likely to be. 

 A minimum limit of thirty-three bees is suggested. 

 Examination of duplicate samples at an interval of 10 

 days will be found valuable. 



Tarsonemus woodi, if present, will be found in the 

 tracheae, occupying the anterior region of the thorax. 

 In bees in which the infestation is well established, 

 httle difficulty will be experienced in detecting the 

 presence of the mites. Should there be bronzing or 

 blackening of portions of the tracheae this also will aid 

 in diagnosis. The greatest source of error likely to 

 arise in diagnosis will occur in connection with cases 

 regarded as free from the parasite. To avoid error here 

 it is imperative that in particular the whole of the 

 primary tracheal trunk on both sides of the body 

 from the spiracular opening inward should be examined. 

 Failure to observe this rule will certainly result in cases 

 of infestation being missed, and too low a percentage 

 will be returned ; also stocks which are not clear of the 



