NOSEMA-DISEASB. 



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. 



jr'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 

 fotmd to be infected. 



As a result of artificial inoculation practically 100 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 

 I made. Table I summarizes the experiments together with the results 

 obtained. 



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



Date of inoculation. 



Period 

 before 

 examina- 

 tion. 



Workers 

 infected. 



Besults 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.. 



Days. 

 8 

 13 

 16 

 19 

 22 

 23 

 48 

 53 

 23 

 42 

 48 

 53 

 162 



Per cent. 

 100 

 100 

 100 

 100 

 40 

 50 

 100 

 100 



100 

 100 

 100 

 100 



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 frequenjbly, 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. 



