NOSEMA-DISEASE. 



11 



the food within the stomach for from 1 to 3 days after the inoculation, 

 but there was no evidence that the parasite had increased in numbers 

 or that it had invaded the tissues. 



SEX. 



Nosema infection is encountered most frequently in workers, al- 

 though drones and queens are susceptible. In nature it is not un- 

 usual to find from 10 to 20 per cent of the workers of diseased colonies 

 infected. Frequently a much higher percentage is encountered. In 

 no instance has the writer found Nosema infection in drones taken 

 from colonies in which the disease occurred in nature. In a few in- 

 stances only were the queens that were examined from such colonies 

 found to be infected. 



As a result of artificial inoculation practically IQO per cent of the 

 workers of the experimental colony become infected. If drones are 

 present a very large percentage of them also become infected. 



Queens in experimental colonies may or may not be found infected. 

 To obtain data relative to queens a number of inoculations were 

 made. Table I sununarizes the experiments together with the results 

 obtained. 



Table I. — Nosema infection in queens in experiTnental colonies. 



Date of inoculation. 



Period 





before 



Workers 



piTamma.- 



infected. 



tion. 





Days. 



Per cent. 



8 



100 



13 



100 



16 



100 



19 



100 



22 



40 



23 



50 



48 



100 



53 



100 



23 

 42 





100 



48 



100 



53 



100 



162 



100 



Results of inoculation. 



Mar. 11, 1913. 



July 12, 1913. 



Do 



Mar. 3, 1914.. 

 Oct. .5, 1914.. 

 Oct. 19, 1914. 

 Oct. 29, 1914. 



Do 



Feb. 4, 1915.. 

 Sept. 16, 1914 

 Nov. 20, 1912 

 Oct. 29, 1912. 

 Aug. 6, 1914. 



Queen not infected. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Queen Nosema infected. 



Do. 



Do. 



Do. 



Do. 



It will be seen from the foregoing table that out of the 13 experi- 

 mental colonies 9 of the queens upon examination were found to be 

 free from infection while the other 5 were infected. Infection in 

 the queen occurs less frequently, apparently, when the inoculations 

 are made in the spring and summer than when made in the autumn 

 or winter. Queens in colonies inoculated and kept at room tempera- 

 ture were found infected in some instances and not in others although 

 practically 100 per cent of the workers in all of them became in- 

 fected. 



