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XXIX. —ISLE OF WIGHT DISEASE IN HIVE BEES. 
(1) The Etiology of the Disease. By John Rennie, D.Se. ; Philip Bruce White, 
B.Sc. ; and Elsie J. Harvey. (With One Plate.) 
(Read November 1, 1920. MS. received December 4, 1920. Issued separately March 25, 1921.) 
Introductory. 
Isle of Wight Bee Disease has been known in this country certainly since 1904, 
when it was first recognised in the island from which it derives its popular name. 
According to Imms it was probably present in Derbyshire in 1902, and was also known 
in Cornwall and other districts in 1904. Prior to these dates periodic losses of bees of 
a serious character are on record, dating as far back as the middle of the eighteenth 
century. Bullamore and Malden (1912) haye summarised fully these outbreaks in. 
historical series in their report in Journal of Board of Agriculture, Supplement 8, 
xix. From a study of the records which they have brought together and from 
personal inquiries which we have made at various bee-keepers of wide experience, 
it would appear that none of these earlier outbreaks attained the general distribu- 
tion throughout the country which we know in Isle of Wight Disease at the present 
date, nor did any of them remain established over such an extensive period of years 
as that which has continued without interruption from 1902 until the present time. 
Another striking characteristic, and one which has an important bearing in any 
investigation which seeks to trace the source of this malady, is the fact that no 
disease of such a permanent and extensive nature has so far been recognised unmis- 
takably outside the British Isles. All the facts we are at present aware of suggest 
its definitely localised and insular character. 
Since 1907 investigations into the cause of this disease have been carried out by 
a series of workers who have from time to time reported upon the subject : Imms 
(1907), Malden (1909), Graham Smith, Fantham, and others (1912 and 1913) in 
England ; and Anderson (1916), Anderson and Rennie (1916), Rennie and Harvey, 
No. 1 (1919) and No. 2 (1919), in Scotland. 
The net result of these investigations has been that the English workers (Graham 
Smith et alii, 1912 and 1913) put forward as the causal organism the protozoan, 
Nosema apis. It is due to Anderson amongst the Scottish workers to state that 
he was the first to call this conclusion in question, and we think that the later work 
referred to above (Anderson and Rennie, and Rennie and Harvey, 1919) has succeeded 
in establishing (l) that Isle of Wight disease and Nosema infection are not 
coincident, and (2) that there exists a distinct 'disease due to Nosema apis, which 
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