Bacterial Disease of the Squash-hug. 373 



Both laboratory and field experiments show that the 

 disease is readily communicated to healthy squash-bugs 

 by contact with the fluids of infected insects, nymphs 

 being- more easily affected than adults. 



Fresh agar cultures of the bacillus are effective as 

 sources of infection. 



The disease may be communicated to young chinch- 

 bugs either from diseased insects or from cultures; but 

 adult chinch-bugs are strongly resistant. 



With the grubs and other larvae hitherto experimented 

 upon, external applications of infection material have 

 given no successful results. 



Infusions from the growth on agar contain an active 

 principle which kills many insects after a very short 

 period of immersion. 



Sections of diseased squash-bugs show that the bacillus 

 is present in the blood at all stages of the disease. The 

 hypodermis, adipose tissue, and cardiac tissue are also 

 early affected. When death ensues the body fluids are 

 like pure cultures of the disease organism; and accom- 

 panying saprophytic germs are seldom found. 



ACKNOWLEDGMENTS. 



To the Director of the State Laboratory of Natural 

 History, Professor S. A. Forbes, I owe many thanks for 

 the opportunity of working upon the disease herein dis- 

 cussed, as it is to him that the Department of Insect 

 Disease Work owes its origin. I would also express my 

 thanks to Mr. W. G. Johnson for valuable assistance 

 with various entomological details. 



BIBLIOGRAPHICAIy, 



The list appended deals only with bacterial or so-called 

 bacterial diseases of insects, and in it are included all 

 works and articles to which I have had access, together 

 with tlip ni;iioi-itv of references definitelv given in these 



