Contagious Diseases of Insects. 259 



cabbage worm {Pieris rapce), first observed by us at Normal. 

 September 11, 18S3. The bacterial character of this disease 

 was ascertained, many attempts at cultures were made, some of 

 them successful, and the possibility of conveying the disease to 

 a distance by means of affected cabbage worms was tested by 

 us in Western Illinois and Iowa. Many of the observations 

 and experiments relating to fiacherie in this insect were re- 

 peated by me in 1884. and in the early summer of 1885 admi- 

 rable photographs of several of the slides were made for me by 

 Dr. H. J. Detmers, of Champaign. 



" Jaundice " of the silkworm appearing in an experimental 

 nursery of this species, under the charge of Professor Burrill 

 at the State Industrial University, at Champaign, in June, 1884, 

 an opportunity was afforded me to study this affection. Many 

 successful cultures were made of the bacteria involved, and 

 several experiments were undertaken for the infection of healthy 

 cabbage worms with the contagion from these artificial cultures. 

 Succeeding in the laboratory, these experiments were can-ied 

 into the field, and attempted on the large scale of actual 

 practice. 



An epidemic of muscardine appearing in certain breeding 

 cages of the forest tent-caterpillar (CUsiocamjm sylvatica) in 

 June, 1884, this disease was studied by us as there illustrated, 

 and connected more or less certainly with a destructive epidemic 

 of the preceding year, which had swept away vast numbers of 

 that species under my observation in Southern Illinois. 



With the exception of the fiacherie of the chinch bug, 

 these observations have not hitherto been anywhere fully re- 

 ported, although brief notices and general accounts of a more 

 or less popular character have been printed in the scientific 

 journals and in some economic publications. 



The chinch bug observations were published, as already 

 mentioned, in the Twelfth Report of the State Entomologist 

 of Illinois, the species of Micrococcus concerned having been 

 previously described by Prof. Burrill in the Report of the 

 Trustees of the Illinois Industrial University for 1882, and in 

 the " American Naturalist " for March, 1883. 



A brief preliminary paper on fiacherie of Datana was read 

 to the entomolosical club of the American Association for the 



