92 THE EEPOET OP THE Js^. 36 



As a result of his work in Soutli Africa Lounsbury, in 1913, came to the con- 

 clusion that in this country the method of d'Herelle can be used only as a supple- 

 mentary measure, and that only under certain conditions. It cannot be used as a 

 substitute for arsenical poisoning. 



Further work in Algeria, in Tunisia and in Morocco, has demonstrated that 

 this method can bring about a considerable reduction in the size of the swarms 

 of the migratory locusts which invade these countries. In each case it was found 

 possible to create an epizootic centre by placing a few diseased locusts among the 

 healthy ones. 



In the summer of this year (1916) at the request of Dr. Hewitt, the Dominion 

 Entomologist, we conducted experiments at Macdonald College, to determine 

 whether d'Herelle's infection method could be effectively used in combating the 

 locusts of Eastern Canada. 



Increasing the Virulence of the Organism. D'Herelle found that when kept 

 for some time in artificial culture the organism gradually loses its virulence, but 

 that the virulence could be progressively increased by passing the organism succes- 

 sively through a series of locusts. The culture sent us by Dr. Hewitt was obtained 

 by him from d'Herelle, and was consequently quite old when our work was com- 

 menced. In order to obtain an active culture, and to have this on hand for daily 

 use, we inoculated several locusts each day with a suspension of the intestinal con- 

 tents of one of the locusts dead from the previous day's inoculation. 



The first lot of nymphs was inoculated directly with d'Herelle's pure culture. 

 At the end of twenty-four hours thirty-three per cent, were dead, and at the end of 

 forty-eight hours fifty per cent. In five days all of the inoculated locusts had 

 succumbed to the disease. Plates poured from the intestines of the dead locusts 

 gave a pure culture of CoccohaciUvs acridiorum. One of the locusts Avhich had died' 

 during the first twenty-four hours was carefully opened with sterilized instruments 

 and a suspension of a portion of its intestinal contents made in sterilized water. 

 This suspension was used to inoculate the second lot of locusts. This second lot 

 died slowly, only 83 per cent, having perished at the end of five days. The third 

 and fourth lots showed an increase in the virulence of the organism, but in each 

 case there were three insects surviving after twenty-three days. Of the sixth lot 

 sixty per cent, were dead at the end of twenty-one hours and the remaining forty 

 per cent, at the end of thirty-four hours. Sixty-four per cent, of the seventh lot 

 died in twenty-two hours, and the remainder were all dead within thirty hours from 

 the time of inoculation. After this the virulence of the organism progressively 

 increased; no locusts survived, the deaths occurring in four to twelve hours. Thus 

 our experience in increasing the virulence of the organism coincides with that of 

 other workers. 



Insects Affected hij the Disease. The pathogenicity of the organism was tested 

 for all species of locusts and grasshoppers commonly occurring in this region. These 

 were Melanophis femur-rubnon, M. bivittatus, M. ailanis, Dissosteira Carolina, 

 Camnulo) pellucida, Stenobothrus curtipen?iis and Xiphidiiim- sp. The cocco- 

 bacillus proved to be pathogenic to all these species. It gave us considerable satis- 

 faction to observe that the animal parasites were apparently not affected by the 

 disease. Innumerable individuals of Gordius emerged alive from inoculated locusts, 

 and we were able also to rear several adult Sareopliagids from these diseased 

 insects. 



An Indigenous Organism. On August 16th, before any experiments were 

 started outdoors, a dying bivittatus was found about a quarter of a mile away 



