354 Illinois State Laboratory of Natural History. 



bugs out of previous experimental lots was employed in 

 the same manner as above, in this case one gill of water 

 being used. This was sprayed upon two hundred or more 

 half-grown nymphs and adults infesting a squash-vine, 

 and the vine then securely covered with mosquito netting. 

 The weather continued quite cool, and on the fourth 

 day after infection fourteen dead bugs were found, all 

 but two of which showed the disease characteristics. 

 On the seventh day there was a total of thirty-two dead 

 bugs. A frost the previous day killed the food leaves, 

 but the stems were still in good condition. This cold so 

 chilled the bugs that they moved very little during the 

 early part of the day; yet an examination of the field, 

 as a check, gave no dead insects which might not have 

 died from injuries by persons passing about. On the 

 tenth (\ixy thirteen recent deaths had resulted ; and in 

 spite of the precautions taken, many of the bugs had 

 escaped, the wind having frequently displaced the netting. 

 After the twelfth day, October 9, the netting was re- 

 moved and only one additional count made, the small 

 number of bugs remaining not justifying further observa- 

 tions. A summary of the results is as follows: 



September 27, about two hundred squash-bugs were 

 sprayed with infusion of diseased bugs. October 1, fojLir- 

 teen dead insects were counted, and later, additional 

 ones, as follows : Octobei' 4, eighteen ; October 7, thir- 

 teen ; October 9, seven ; and October 15, three — a total 

 of fifty-five. 



Experiment 17. — Parallel with the above and on the 

 same date (September 27), an experiment was made to 

 test in the field the efficiency of old pure cultures of this 

 organism. The growth from two tubes one month old 

 was diffused in a gill of water, and sprayed upon the 

 insects as before. There were, however, more than two 

 hundred bugs present under the netting in this experi- 

 ment. Four were dead October 1, and subsequent counts 

 of additional dead were as follows: Oct. 4, two; Oct. 7, 



