72 



(b) Example of Naturally Occurring Outbreak of Isle of Wight 

 Disease, showing Spontaneous Eecovery. 



Craibstone Apiary. 



On 4th June 1915, three strong stocks of bees imported from Devonshire 

 were placed in this newly constituted apiary and housed in perfectly fresh 

 hives. During the fine weather of June they were very prosperous, each 

 stock swarming once and one of them twice. The swarms were hived 

 separately. Three races were represented, viz. pure Italian, pure Carniolan 

 (queen imported from Austria in 1914), and ordinary black bees. 



Symptoms of Isle of Wight disease made their appearance on 30th June, 

 and continued, with fluctuations, till near the end of August. All the 

 stocks and swarms were affected more or less, but the heaviest mortality 

 occurred in the blacks (D4). Three of the seven stocks died out owing to 

 their failure to mate the virgin queens. In all three cases drone breeders 

 were developed. On 22nd September four stocks survived and no symptoms 

 of Isle of Wight disease were apparent, either in the behaviour of the 

 bees, which was perfectly normal, or in the condition of their internal 

 organs. At no stage of the disease were spores of Nosema found, although 

 repeated examinations of the contents of the alimentary canal were 

 made. 



While the disease was at its height the number of affected bees was 

 very great. Their behaviour was of the usual character, and the walk leading 

 from the hives was littered with crawling bees to a distance of at least 

 25 yards. Heaps lay on the flower-beds, and a low box-hedge was full of 

 bees incapable of flight. 



The mortality was, in consequence, very considerable, and the weather 

 conditions were exceedingly unfavourable to bee life. The recovery is 

 thereibre all the more notable. 



On 22nd September one of the stocks (D4) was decidedly weak. It was 

 headed by a young queen, had brood on two combs and plenty of store for 

 the number of bees. This is the stock which had the heaviest mortality 

 during the crawling period. Two other stocks (Al and C3) were in 

 excellent condition for wintering, headed by young queens, populous as 

 to bees, and with plenty of stores. The fourth stock (B2) is the only one 

 now that is not headed by a queen of this year. Possibly on this account, 

 and also on account of heavy losses during the crawling period, this stock 

 is also rather short of bees. The queens in D4 and B2 are black, C3 has 

 a young Carniolan queen. Al, originally pure Italian, is now filled with 

 dark bees, the offspring of a young queen. 



