56 Annals E^itomological Society of America [Vol. X, 



Experiments in the Open Field : 



Two unsuccessful attempts were made to create an epizootic 

 centre in the open field. 



Experiment 1. The first attempt was made in a clover field 

 badly infested with M. femur-rubrum. A small area of this field 

 was treated with the infected bran mash. The field was exam- 

 ined daily but comparatively few dead locusts and no evidences 

 of an epizootic were found. Numbers of locusts were collected 

 from this field and placed in insect cages but the disease did not 

 develop among them. 



Experiment 2. A similar experiment was conducted on a 

 badly infested lawn with the same results. 



G. Conclusions. 



The results of our work indicate that d'Herelle's biological 

 method for the control of locusts cannot take the place of the 

 methods now in use under the conditions which obtain in 

 Eastern Canada. Should the disease become established, its 

 spread would be extremely slow owing to the non-migratory and 

 non-cannibalistic habits of the native species. The ideal con- 

 ditions for the .effective use of this method are those such as 

 d'Herelle and others found in South America and North Africa 

 where the locusts were in quickly moving swarms and were 

 markedly cannibalistic in their habits. Indeed, most of these 

 writers have emphasized the fact that " acridiophagy " is the 

 chief factor in the spread of the disease. Another hindrance to 

 the effective use of this method lies in the presence of several 

 native strains of a coccobacillus identical with or closely related 

 to d'Herelle's. These organisms are undoubtedly responsible 

 for the immunity of the locusts to a mild infection of Coccoba- 

 cillus acridiorum. 



PART II. DESCRIPTIVE STUDIES ON COCCOBACILLUS ACRIDIORUM 

 d'hERELLE, and SIXTEEN RELATED NATIVE ORGANISMS. 



During the early part of our work we made plates daily 

 from the intestinal contents of dead locusts. In every case we 

 got a pure culture of the organism. The culture medium used 

 was 1% beef peptone agar and the plates were kept at room 

 temperature (about 30° C). The growth under these condi- 

 tions is rapid. The colonies are spreading and filmy and not 



