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difficulty in killing mites in bees isolated in cages has 

 been encountered, but in illustration of the difficulties 

 apart from those already enumerated, it may be men- 

 tioned that in most trials it has been the rule to 

 experience considerable irregularity in results. The 

 same substance in the same concentration, applied for 

 the same length of time, may kill mites in one bee and 

 not in another. The mortality amongst the bees in 

 control cages varies in a similar way. 



The same uncertainty has resulted when tests have 

 been made with complete colonies. Substances which 

 beyond question are lethal to the mites and which can 

 be used without serious mortality amongst the bees, 

 even when applied over prolonged periods, fail to 

 absolutely clear the colony to the last mite. But not- 

 withstanding this, by a combination of anti-acarine 

 management such as I have already suggested, and 

 treatment where this has been begun when the incidence 

 of infestation was low, success in preventing the collapse 

 of colonies and in maintaining such stocks profitably 

 has been attained. 



While it must be distinctly stated that I put forward 

 no claim to have yet finally solved the problem of 

 Acarine disease control, on which I am continuing my 

 investigations, in response to many and continued 

 appeals for the supply of provisional treatment, I have 

 decided to commit myself to the following recommenda- 

 tions, selected from a list of tests all of which have had 

 a measure of success. These are given in the midst of 

 much highly promising but uncompleted work, and are 

 put forward not as final advice, but more particularly 

 for seasonal reasons, in order that some help may be 

 available in the present autumn. On general groxmds, 

 as regards treatment, autumn undoubtedly offers the 

 safest and most effective opportunities for the intro- 

 duction of noxious substances to bee hives, and it is 

 hoped the advice will be followed now by those who 

 approve this method of control. Spring, to a lesser 

 degree, affords similar advantages, and the suggested 

 treatment is applicable there also ; summer, on the 

 other hand, is the season in which effective manage- 

 ment rather than treatment should be pursued. In 

 this way all risk to brood or of contamination to honey 



