Bacterial Disease of the Squash- bug. 343 



ventral surface of the abdomen. Later, the wet appear- 

 pearance is more evident throughout; but the bard 

 chitinous crust does not shrink or collapse, and unless 

 broken, the offensive fluids within are unnoticed. In all 

 cases, the odor — more pronounced and putrefactive than 

 the normal squash-bug odor— is especially characteristic. 

 A short time after death the appendages are very readily 

 separable at the articulations, and it is almost impossi- 

 ble to lift an insect by means of them. 



A long series of infection experiments will be described 

 later, and in this connection it is only necessary to note 

 further the post-mortem appearances of insects free from 

 this disease. It has been established that bacteria are 

 normally found in the ccecal appendages of many Hemip- 

 tera,* among which are the squash-bugs. It conse- 

 quently seemed of interest to ascertain if these bacteria 

 might become truly pathogenic, or, at least, cause the 

 peculiar post-mortem appearances under abnormal condi- 

 tions — as of lessened food supply. Such investigation 

 was quite superfluous in view of the check experiment 

 above recorded, but, nevertheless, a few healthy indi- 

 viduals were allowed to die from gradual starvation. 

 Under these conditions the body cavity gradually dried 

 out, and when death finally resulted the shell was greatly 

 contracted in the abdominal region, and slightly drawn 

 together ventrally. This was especially true of the 

 nymphs, and later observations were to the same effect. 

 Lessened vitality may encourage the disease, but it 

 has nothing to do with a "spontaneous" occurrence. 

 Moreover, the microscopic characters and the cultiva- 

 tion experiments enumerated later show conclusively 

 that the disease form is entirely distinct from the normal 

 form. 



Other nymphs were killed by immersion in the toxic 

 bacterial infusion from a pure culture of the disease or- 

 ganism, — which toxic infusion will be subsequently, de- 



* "Bacteria Normal to Digestive Organs of Hemiptera." By S. A. Forbes. 

 (Bull. 111. State Lab. Nat. Hist, Vol. IV., pp. 1-7.) 



