26o Journal of Agricultural Research voi. v. No. 6 



From these cage experiments therefore it would appear that the wilt 

 bacteria are carried over the winter by the hibernating beetles and inocu- 

 lated into the cucumbers as they feed upon the young leaves. However, 

 from the fact that wilt appeared in only one of the four cages into 

 which beetles were introduced, it would seem that not all hibernating 

 beetles carry the disease, but only those, or some of those, which have 

 previously fed upon wilted plants. In other words, the beetles act not 

 only as summer but also as winter carriers of the wilt organism from one 

 cucumber plant to another. At least the above facts seem to warrant 

 this as a tentative conclusion. The only possible alternative is to sup- 

 pose that some of the beetles captured on June 17 and introduced into 

 the four cages had recently had opportunity to gnaw diseased plants, 

 which under the circumstances of their capture appears to the writer out 

 of the question. Finally, in addition to the positive evidence of insect 

 transmission afforded by this cage and by the one into which a beetle 

 accidentally penetrated, as well as by daily observation on the check 

 plants, there is the negative evidence afforded by the fact that in all 

 cages from which beetles were excluded the plants remained free from 

 the disease in two fields where it was very prevalent. 



