Bacterial Disease of the Squash-bug. 355 



thirteen; Oct. 9, four; and Oct. 15, one — making a total 

 of twenty-four. 



As the weather was unfavorable for the spread of the 

 disease when once established, these experiments must 

 be judged wholly in the light of results accruing from 

 the original infection alone. Evidently the old cultures 

 were not as effective as the infusions from dead bugs, and 

 the difference is even grea,ter than is apparent from the 

 summaries, for there were more insects in Experiment 17 

 than in No. 16, and fewer bugs escaped towards the 

 later periods of observation. There is every reason to 

 believe that this disease may be spread among squash- 

 bugs in the field. 



INFECTION EXPERIMENTS W'lTH THE CHINCH-BUG 



{Blissus leucopterus Say). 



The first infection experiments with chinch-bugs, made 

 in the early part of August, were vvholly unsatisfactory, 

 owing to the spent condition of the bugs of the first 

 brood, and the results are not included in this paper. 

 When the second brood began to make its appearance, 

 late in August, all previous experiments were repeated 

 and new ones were begun. 



The majority of bugs involved in the series of experi- 

 ments tabulated below were in the first stage — a few in 

 the second. In each case a large tumbler about one 

 third filled with moist sand and covered with a muslin 

 cloth was the cage extemporized as best adapted for this 

 purpose. The vessels and the sand were previously steril- 

 ized, and stalks of Indian corn cut into suitable pieces 

 were regularly supplied as fresh food. A small pill-box 

 of the bugs, approximately five hundred, were then 

 momentarily immersed in the infusions used, or immedi- 

 ately put into the cage with the infection material. The 

 number of dead bugs in each cage was ascertained by 

 actual count, and is given below. 



