ON ISLE OF WIGHT DISEASE IN HIVE BEES— ETIOLOGY. 177 



" healthy " in the sense that it belonged to a colony which had no history of disease 

 and was regarded as free from such. In the following May, Mr White made the 

 further and independent discovery that mites in all stages of development occurred 

 in certain of the major thoracic tracheae of " crawling " bees. In reporting this 

 discovery he stated that he had found this condition in at least 150 sick bees, repre- 

 sentative of several diseased stocks, and also that he had failed to find mites in 

 95 per cent, of apparently healthy bees.* On this occasion he expressed the view 

 that the parasites seen by him bore a definite etiological relationship to the disease. 



That this discovery was one of very great significance was obvious, and the 

 senior author immediately proceeded to its further verification. The first stock of 

 bees examined was one in a highly prosperous condition. The bees were occupying 

 twenty frames in the latter half of May ; they were working splendidly and a source 

 of great satisfaction to the owner. Twelve flying bees were captured as they entered 

 the hive. They were taken to the laboratory and the first bee opened was found to 

 contain the parasite in limited numbers. All the twelve were examined, and of the 

 remaining eleven, one other was found also to be harbouring the mite in question. 



These facts presented, as in a nutshell, the problem confronting us. It was 

 evident that the distribution was not limited to those bees or stocks hitherto 

 regarded as " sick," and as the result of the extensive investigations which followed 

 and which are now recorded, we are able to announce that notwithstanding 

 variations in the course of the disease in different stocks, we regard it as established 

 that there is an invariable association of the parasite with diseased stocks, and that 

 there is a definite pathology in relation to infection in the individual bee. 



Incidence of Infection within the Colony. 



Brood. — -Except in one doubtful case we have not found infection with Tarso- 

 nemus in brood of any stage, nor has it been found amongst the very youngest 

 of adult bees. 



Workers. — Amongst workers the infection is most marked in the older bee, and 

 in any case it has not been found except in incipient stages amongst nurse bees 

 whose adult life has been brief. 



Drones. — We have found that drones of affected stocks suffer equally along with 

 the workers. 



Queens. — The important and interesting question of the relation of the queen in 

 this connection has been investigated by one of us (J. R.) in a limited number of cases. 

 Of fifteen queens examined of stocks known to be affected with this disease, ten were 

 found to be free, whilst the remaining five harboured this organism. That queens 

 may undergo infection is specially interesting, in view of the familiar fact that the 



* The systematic examination which followed showed the number of apparently healthy stocks harbouring the 

 parasite to be as high as 36 per cent. (J. R.) 



