The Occurrence of Diseases of Adult Bees, II. 17 



of other species in and about beehives, and repeats the records of the 

 finding of Tarsonemus tvoodi in Switzerland just mentioned. At the 

 time of the writing of this article he had been unable to find living 

 mites in the thoracic trachea? of bees from those colonies in which 

 they were found dead on bees which had died during the previous 

 winter, but he specifically states that he does not question the state- 

 ment that it is the cause of the Isle of Wight disease. 



The most recent discussion of the situation, which covers the 

 ground as it is so far understood in Switzerland, is contained in 

 an interesting lecture (44-) which Morgenthaler delivered before the 

 Wanclerversammlimg des Vereins deutschschweizerischer Bienen- 

 freunde on August 20, 1922, in Brugg. This lecture deals briefly 

 with most of the diseases of adult bees, but the portion which is of 

 special interest is that part dealing with his results with the mite. 

 It may be mentioned that he finds that the protozoan parasite 

 Xosema apis is in Switzerland, as in America, usually a relatively 

 harmless parasite, but that under certain circumstances it produces 

 a serious disease. Morgenthaler is inclined to believe, so far as can 

 be judged from his lecture, that Nosema apis and Acarapis ivoodi 

 are usually about of equal destructiveness to the colonies, but it is 

 not quite clear as yet what the circumstances are which increase 

 their damaging characteristics. 



He reports that the mite has now been found throughout Switzer- 

 land. This is a small country, enabling him in one season to make 

 a rather complete survey, but he records finding the mite through- 

 out the country. The virulent cases were found in the Cantons of 

 Geneva and Vaud (adjacent to France), while the worst case was in 

 the middle of the Canton of Yalais (adjacent to Italy). He re- 

 ports five such virulent cases, and in a private communication he 

 reports a sixth case. Regarding the more general distribution of 

 the mite in the milder or chronic cases, he states (4-4) : 



And indeed these mite-infested apiaries were found scattered through the 

 whole country, among others also on our northern, southern, eastern, and 

 western boundaries, so that it may be surmised that the mite is also scattered 

 in neighboring lands and will be found as soon as it is sought. Switzerland 

 may therefore not be considered as an especially dangerous center of infec- 

 tion of the acarine disease. 



Regarding the worst case of infection, in middle Yalais, he states : 



The acarine disease in its virulent form has been found in Switzerland in 

 five apiaries * * * but worst in a little village in middle Valais, where all 

 three apiaries of the place were attacked. Here the occurrence of the disease 

 may be traced back with certainty to the year 1915, and the chief sufferer — 

 incidentally it may be noted, an excellent beekeeper, bee inspector, and teacher 

 of beekeeping in an agricultural school — has in this time lost 26 of his 35 

 colonies. Importation of bees from England has nowhere occurred. 



The record for Switzerland can not be interpreted as consisting 

 of cases directly attributable to importations, 6 'and one must con- 



6 In a recent article Fr. Leuenberger (Jahresbericht fiber die Faulbrutversicheiung des 

 V[ereins] D[eutsch] S[chweizerischer] B[ienenfreunde] pro 1922, in Schweizerische 

 Bienen-Zeitung, n. f., v. 46 (1923), no. 3, p. 115-120), who has charge of the bee disease 

 control work in Switzerland, states the Isle of Wight disease occurs in increasing amounts 

 in French Switzerland and that apparently it has been brought in through importation of 

 bees from western France. No case of the disease is reported by him from Genua n 

 Switzerland. He expresses the hope that the disease may be localized by energetic 

 measures before it causes greater damage, but does not report the nature of the measures 

 adopted. Morgenthaler (.',!,) reports finding the mite on the northern boundary of 

 Switzerland (German Switzerland). 



53546°— 23 3 



