1917 EXTOMOLOGICAL SOCIETY. !);3 



from the laboratory. The intestines were decayed into a Ijlaek mass resembling that 

 of insects killed by C. acridiorum. but not quite so slimy. Agar plates were made 

 from the contents of the intestines and a practically pure culture of a bacillus 

 closely resembling that under study was obtained. Twenty locusts were inoculated 

 with this organism, and all but one died within forty-eight hours. From these 

 dead locusts a series of successive inoculations was made to determine whether the 

 organism M'ould increase in virulence similarly to C. acridiorum. We found that 

 this was the case; the later ones in the series dying very much sooner than the 

 earlier ones. 



A very large number of other locusts, healthy, sickly or dead were collected 

 on ]\Iontreal Island, and other islands in the Ottawa as well as on the mainland 

 along the north shore of the Ottawa. ]n almost every case this organism was found 

 in the intestines. "We are at present making a study of it to determine whether it 

 belongs to the same group as Coccobacillus acridiorum. 



ExPEItlJIEKTS IX THE LaBORATOKY. 



In order to become acquainted with the nature of the disease before working 

 with it iu the field, we conducted numerous experiments in the laboratory, the 

 results of which are here briefly summarized. 



Several locusts were sprayed with a suspension of the coccobacillus, and put 

 into a sterilized cage. At the end of eight days fifty per cent, of these Avere dead. 

 The others remained alive for several days after when their death could not Avith 

 certainty be attril)uted to the organism, because several of the dead locusts were 

 parasitized, and it was often difficidt to tell whether death was due to the disease or 

 to animal parasites; it must therefore be borne in mind that an appreciable pro- 

 portion of the deaths recorded in this and other experiments w^as probably due to 

 parasites. 



Experiments were tried to determine whetlier the disease would spread rapidly 

 from dead or diseased locusts to healthy ones. To this end a number of healthy 

 insects were placed in cages with dead ones. The species used was largely 

 M. femur-rvhrum with a few individuals of other species. A very low mortality was 

 obtained. It was obs«3rved, however, that occasionally a hivittatus would feed on 

 the dead insects, and in order to determine the effect of this habit on the spread 

 of infection M. hivittafus and M. femnr-ruhrum were placed in equal numbers in 

 a cage with fragments of dead locusts. At the end of eight days eighty per cent, 

 of hivittatus were dead, and only twenty per cent, jemur-ruhrum. In this con- 

 nection it may be stated that in the cases in which investigators have obtained 

 successful results in the artificial dissemination of Coccohacillus acridiorum the 

 locusts experimented upon showed marked cannibalistic tendencies, the healthy 

 ones devouring the sick and dead. 



Placing healthy locusts in unsterilized cages in which diseased locusts had been 

 confined and had died but a fcAV hours previously caused no disease or death. 



A number of locusts were fed with a bran mash to which a suspension of 

 C. acridiorum had been added. At the end of seven days fifty per cent, were dead, 

 four days later the mortality had reached seventy-five per cent. The remainder 

 were removed to a clean cage, and eight days after their removal were all dead. 

 It is thus evident that ingestion of the organism will produce disease and death. 



