192 ISLE OF WIGHT DISEASE IN HIVE BEES— ETIOLOGY. 



infection within a stock is not likely to occur. Yet apart from any special combina- 

 tion of adverse factors, it appears to be common for the disease to steadily gain 

 ground %Wthin a stock once it is established. It is, however, clear that no sound 

 argument against the view that Tarsonemus is the cause can be built up from cases 

 where, in the presence of Tarsonemus, disease did not spread within the stock and 

 destroy it as a whole, so long as it can be shown that there is an associated pathology 

 which in due course renders the infected bees ineffective members of the colony, and 

 all the time causes loss of bees by crawling or directly by death. 



LITERATURE CITED. 



An'DBBSon, John (1916), "The Connection of Nosema apis and Isle of Wight Disease in Hive Bees," 



Proc. Roy. Phys. Soc. Edin., xx, p. 16. 

 Anderson and Rennik (1916), "Observation and Experiments bearing on Isle of Wight Disease in Hive 



Bees," Proc. Roy. Phys. Soe. Edin., xx, p. 23. 

 Graham Smith, Fantham, and others (1912), "Report on the Isle of Wight Bee Disease," Supplement 8, 



Journ. Board of Agric, xix. 



(1913), "Further Report on the Isle of Wight Disease," Supplement 10, Journ. Board of Agric, xx. 



Ihms, a. D. (1907), " Report on a Disease in Bees in the Isle of Wight," Journ. Board of Agric, xiv, p. 129. 



Maldkn, W. (1909), "Disease of Bees in the Isle of Wight," Journ. Board of Agric, xv, p. 809. 



Rennib and Harvky (1919), (1) "Isle of Wight Disease in Hive Bees," Journ. Scott. Board of Agric, ii, 



p. 176. 



(1919), (2) " Nosema apis in Hive Bees," Journ. Scott. Board of Agric,, ii, p. 511. 



White, G. F. (1919), "Nosema Disease," U.S. Dept. Agric. Bureau of Entomology Bull. No. 780. 



EXPLANATION OF FIGURES. 



All the figures are photographed with Watson Service Microscope. 



Fig. 1. Tarsonemus in trachea of hive bee. The first specimen observed. A. Tarsonemus. B. trachea, 

 C. thoracic glands. ^ in. oil imm. obj., ocular No. 2. 



Fig. 2. Teased preparation of infected trachea showing' various stages of Tarsonemus. j in. obj., 

 ocular No. 2. 



Figs. 3, 4, and 5. Tracheae containing Tarsonemus. 



Fig. 3 shows the blackening of the tubes. . 



Fig. 5 shows blocking of wider tube with larval stages. \ in. obj., ocular No. 4. 

 Fig. 5, ocular No. 4. 

 Fig. 6. Section of infested trachea wall. A. not badly affected. Mites seen in section. \ in. obj., 

 ocular No. 4. 



Fig. 7. Do., showing A. thickening of wall of tube. B. Two ovigerous females in situ. ^ in. obj., 

 ocular No. 2. 



