Mites Injurious to Domestic Animals. 103 



the year, the age and qualities of the queen, the district and amount 

 of disease prevalent within it, the proximity of other stocks either 

 in the same or other apiaries. The advice of experts should be 

 taken in estimating the particular importance to be attached to 

 these matters." 



Investigations on the treatment and prevention of this disease 

 are being carried on at the University of Aberdeen and elsewhere. 

 The instructions given above are therefore necessarily of a pre- 

 liminary nature. As our knowledge of the malady increases 

 improved methods will be discovered. 



Traps for crawlers, although no doubt very useful, only help in 

 the elimination of very heavily infected bees. Many bees which 

 have the mites in their tracheal tubes are still capable of flight. 



During the height of the season, bees from neighbouring stocks 

 when bringing in nectar sometimes attempt to enter the wrong hive, 

 and, if laden, are usually admitted. It is difficult to imagine any 

 way by which this intermingling could be entirely prevented. Drones 

 also visit strange hives, and although they can be prevented from 

 entering, the devices used for this purpose are not very practical, in- 

 asmuch as they interfere with the normal life of the bee community. 



Mites are very resistant to chemical fumes, and it seems very 

 unlikely that any method of fumigation can be discovered that 

 will kill the mite without injuring the health of the bee. It seems 

 probable that drastic methods, such as compulsory notification and 

 destruction of all diseased stocks, will finally have to be adopted in 

 dealing with this malignant disease of bees. 



ON MOUNTING MITES FOR EXAMINATION 

 UNDER THE MICROSCOPE. 



For ordinary research purposes it is best to mount mites in 

 glycerine jelly or in glycerine diluted with water. Owing to its 

 higher refractive index, balsam is not a very suitable medium for 

 mounting Acari, for it is difficult to see delicately chitinized plates, 

 etc., when it is used. In order to study the external morphology 

 of mites it is usually necessary to destroy as far as possible the 

 muscles and other internal structures by soaking in 10 per cent, 

 caustic potash solution. Spirit specimens of parasitic Gamasid 

 mites often contain coagulated blood, which is very difficult to 

 dissolve ; they should be pricked with a very fine needle and well 

 boiled in caustic potash, the blood when sufficiently softened being 



