Bacterial Disease of the Squash-hug. 353 



to yield the disease orc^anism; and, moreover, one of 

 the bugs immersed for a very short time in the infusion 

 from this grasshopper was killed. This grasshopper had 

 been dead for about two days, however, and this may 

 have injuriously affected the disease organism. 



Field Experiintnts. 



Experhneiit 15. — A careful examination of a squash 

 patch on the Agricultural Experiment Station grounds 

 on Sept. 17 resulted in a find of two dead squash-bugs; 

 but microscopic examination showed that the bacteria 

 in the bodies of these insects were different from the 

 disease bacillus. It was doubtful if the disease existed 

 in the field at all at this time, and a field infection 

 test was greatly to be desired. For this purpose several 

 dead bugs from Experiment 1 were teased out in about 

 40 cc. of water, and this infusion was sprayed upon a 

 squash-vine containing about two hundred bugs. This 

 vine was somewhat isolated from the remainder of the 

 plat. No attempt was made to get the infusion on all 

 of the bugs; but the spi'ay was simply directed to those 

 leaves containing the largest number of insects. The 

 result of the first infection alone was desired, so the 

 dead bugs were removed as soon as found. Three dead 

 insects and three distinctly sick, all njnnphs, were re- 

 moved on the second day, the true disease bacillus being 

 found in all of their bodies. On the third day eight dead 

 insects were removed, and the number of bugs on the 

 vine was much reduced, owing to migration for fresher 

 food supply. One week after infection the total number 

 of diseased insects amounted to eighteen ; but before 

 this time nearly all of the bugs had migrated, and the 

 exjiei'iment was discontinued. 



Experiment 7^.— Although the season was far advanced, 



and the weather probably too cool for the best results, 



I was encouraged to repeat Experiment 15, with yjre- 



cautions against migration. An infusion of ten dead 



23— 



