94 THE EEPORT OF THE No. 36 



Field Expeuiments. 



An attempt was made to establisli an epizootic centre in a field of clover badly 

 infested with M. femur-ruhrum, and to a lesser extent with most of the other 

 species used in the laboratory. A small area of this field was treated with bran 

 mash, to which a culture of the organism had been added. The field was examined 

 carefully for several days, but no evidence of the establishment of an epidemic 

 among the locusts could be obtained. A large number of locusts was collected 

 from the infected area and placed in cages in the laboratory, but the disease failed 

 to develop among them. The experiment was repeated on a badly infested lawn 

 with a similar result. 



In order to check results more definitely outdoors, a small area of a lawn was 

 enclosed with a wire screen, and a large number of locusts included. First of all 

 the enclosed area was sprayed with a bouillon culture of the coccobacillus. At the 

 end of a week there were no deaths. The failure of this experiment may have been 

 partially due to the death of the organism, as a result of its exposure to bright 

 sunlight. 



The wire cage was next moved to a new locality and bran mash sprinkled on' 

 the grass. From this a high mortality was obtained. 



Twenty locusts inoculated with a virulent culture of the organism were next 

 introduced among the healthy locusts in a new enclosed area. The cage was 

 examined every day, and at the end of the fifth day there were only thirty-nine 

 dead, including the twenty inoculated individuals. The experiment was continued 

 for several days, but no further deaths were observed. 



Conclusion. 



The foregoing investigations point to the conclusion that the infection method 

 of d'Herelle for the control of locusts is not practicable in Eastern Canada, because 

 of the probable immunising efi'ect of a native bacillus, and also because the principal 

 means of the natural dissemination of the organism seems to be the eating of the 

 dead or diseased locusts by the healthy ones, a cannibalistic tendency which exists 

 only in a very slight degree in our native species. 



There may, however, be conditions under which this method may- prove 

 effective, so that we hesitate to say definitely after only one year's work, that it 

 can have no place in control methods in Eastern Canada. 



Dr. Hewitt: Perhaps if I were to explain the genesis of this work it might 

 facilitate discussion afterwards. I have been in correspondence with Dr. d'Herelle 

 for some years, and in 1913 obtained specimens of his culture from him, and had 

 one of our officers, Mr. Fetch, work with it that year, and the two following years, 

 and we found that C. arridiorum was pathogenic toi our native species, especially 

 the species which are most abundant. In 1914, we carried out our first field experi- 

 ments in control, but the climatic conditions were such that we did not feel justified 

 in placing any definite conclusions. In 1915 the conditions were more favorable, 

 and we used the bouillon exactly as d'Herelle had instructed in his letters to me. as 

 well as in his papers, but we were unable in that year with every condition favor- 

 able to find that it could be used in Eastern Canada at least in the Province of 

 Quebec, where these experiments were tried. 



As I knew that the authors of the paper just read were studying the micro- 

 organisms affecting insects, 1 took the matter up with Dr. Harrison, and suggested 

 that they carry on these experiments with C. acridiorum still further, because I 



