284 



were received from twenty-six of the thirty-one remaining cases. Of 

 these twenty-six reports three were unfavorable, nineteen favorable, and 

 four doubtful concerning the saccess of the experiment. These doubt- 

 ful cases are not to be looked upon as unfavorable, but more evidence 

 is needed to transfer them to the list of favorable reports. Thus nine- 

 teen out of twenty-six reports, or 73 per cent., were decidedly favor- 

 able. The experiments will be continued during the season of 1891. 

 In presenting this paper I wish to acknowledge the invaluable aid con- 

 tinually received during the progress of the work from my assistants, 

 Messrs. W. 0. Stevens and V. L. Kellogg. 



The laboratory experiments have been continued through the sea- 

 son. Of the three diseases iudentified, that produced by the Tricho- 

 derma appears to be less fatal than the other two, as is indicated by 

 the following laboratory- notes : 



September 28, dead chinch bugs, showing no signs of fungus exter- 

 nally, were taken from the infection jars and crushed on a glass slide in 

 distilled water. Oval hyphal bodies of a fungus (Trichoderma) were 

 found in considerable number. These were put under a bell jar. 



September 29, some of the hyphal bodies had put out slender myce- 

 lial growths, others in immense numbers were multiplying by division. 



October 1, the hyphal bodies were still multiplying by division. The 

 mycelial growths had become much longer, and in some instances had 

 variously branched. 



Octobers, a dead chinch bug taken from an iufectetl field was crushed 

 on a glass slide in distilled water. Both round and oval hyphal bodies 

 were found in considerable number. These were put under a bell jar to 

 prevent drying. 



October 4, both round and oval hyphal bodies were multiplying by 

 division, and were i^utting out mycelial growths. 



October 5, fresh chinch bugs from an uninfected field \«ere immersed 

 in the liquid containing the above fungi, and were put in a new jar 

 with young corn plants. 



To Mr. Riley's question as to which of the three diseases mentioned 

 was most common in destroying the bugs in the field experiments, Mr. 

 Snow said during the dry summer of the present year he thought the 

 bacterial disease did most of the work, but in 1889 he thought the fun- 

 gous diseases were most destructive. 



Mr. Riley thought that the fact that Mr. Snow had been able to carry 

 healthy bugs through the season without infection in the same room 

 with diseased bugs was a rather discouraging one, as it would indicate 

 either that the germs were easily kept from reaching the bugs or that 

 they were not carried long distances. Close proximity to, or actual 

 contact with, diseased individuals, if necessary, would materially lessen 

 the value of their use in the field, while the evidence of farmers' expe- 

 rience in the field needed very careful weighing, because of the possi- 

 bilities of error. 



