58 Bee Disease 



Three stocks of bees, one Italian, one Carniolan and one black (British or 

 Dutch?) were imported into the apiary from Devonshire on June 4th, 1915. 



During June these three stocks gave off four swarms and the seven colonies 

 were showing crawhng symptoms on June 30th. Three of the colonies died 

 owing to faulty queens and another was destroyed by robber bees. A fifth was 

 reinforced by the addition of three pounds of bees (source not stated) and an 

 Italian queen was also given to this colony. Some driven bees from Wales 

 were placed in the apiary. In December, 1915, there were four stocks alive 

 showing no signs of disease. 



Accounts of further work by Dr Rennie and Miss Harvey (1919 a and b) 

 are given in the Journal of the Scottish Board of Agriculture. With regard to 

 Nosema the conclusion arrived at is that it "is always a weakening factor, 

 and in the presence of other adverse conditions favourable to the development 

 of dysentery it may become seriously pathogenic to bee stocks." In ordinary 

 circumstances it was not found to destroy colonies in the rapid and virulent 

 manner generally found in Isle of Wight disease. The authors consider that 

 in the latter disease there is no recovery of sick bees nor of affected stocks. 



Mention is also made of a temporary sickness which sometimes affected 

 all the bees of a district. "In such cases it would appear to be due to some 

 disturbing factor in the nectar or pollen." 



C. Acarapis (Tarsonemus) woodi. 



In November, 1920, a paper was read before the Royal Society of Edin- 

 burgh in which Dr Rennie, in association with Mr Bruce White and Miss 

 Harvey, described a new species of mite from the tracheae of hive bees. This 

 mite, which was named Tarsonemus woodi, was put forward as being the cause 

 of Isle of Wight disease, which was henceforth to be known as "acarine 

 disease." Hirst (1921) considers that the new mite differs suflaciently from 

 Tarsonemus to form a new genus and proposes that the species shall be 

 renamed Acarapis woodi. 



The mites gain entrance to the tracheae by means of the first pair of 

 thoracic spiracles. Crawhng of bees, followed by the death of the affected 

 colony then takes place. The presence of the mite is not necessarily fatal 

 however, for we read in the Report to the Royal Society of Edinburgh that 



Of 140 stocks believed by their owners to be healthy, 50 or nearly 36 per cent, har- 

 boured the parasite. Concurrent with such discoveries we ascertained by direct examination 

 ourselves of flying bees (1) which were members of colonies in which the disease was definitely 

 estabhshed and (2) which were taken from colonies beheved to be healthy and showing no 

 indications otherwise, that amongst these were to be found considerable numbers harbouring 

 the parasite This was further complicated by the fact that in those infected flying bees 

 certam of those pathological conditions-e.jr. the blackening and hardening of the tracheal 

 tubes-were very marked. As an example it may be quoted that this condition -was found 

 m bees entermg the hive carrying poUen or nectar, both belonging to stocks in which 

 crawhng and other symptoms were weU established and also in those reputed healthy 



