April, '19] O'KANE: LIMITATIONS IN INSECT SUPPRESSION 155 



Mr. McCampbell: When you advise the farmers to spray, how 

 far apart would the sprays be? 



President E. D. Ball: A week or ten days apart. 



Mr. C. p. Gillette: Are the eggs laid wholly on the veins? 



President E. D. Ball: On the midribs and the stalks of the 

 leaves. As soon as they have destroyed the leaves they will feed on 

 the stems and destroy them also. But they feed on the leaves appar- 

 ently up to the time that the leaves die. 



Mr. H. a. Gossard: We had in Ohio the maple injured simi- 

 larly to tipburn and from the association of this species, we attributed 

 it to that. 



President E. D. Ball: This is the leafhopper that injures the 

 growing shoots of nursery stock and young apple trees and burnp 

 them; it is the leafhopper that injures the growing tips of raspberry 

 canes; it is not the leafhopper that injures the leaves of apple trees; it 

 is almost never found on a slow-growing apple tree. On box-elder, 

 it is only found on the water shoots or the fast-growing tips. 



Mr. p. J. Parrott: In Geneva we have a great deal of trouble 

 on the nursery maples. 



Mr. J. T. Headlee: Can the speaker give us some idea of how 

 much an infestation is necessary to bring about the results on potatoes 

 that he describes? 



President E. D. Ball: One leafhopper will destroy a leaf . 



President E. D. Ball: The next paper on the program will be 

 by Mr. O'Kane on "Limitations in Insect Suppression." 



LIMITATIONS IN INSECT SUPPRESSION 

 By W. C. O'Kane 



At the outset there should be some further definition of the subject 

 of this paper. What I have in mind is a brief discussion of some of 

 of the difficulties and problems that arise when the entomologist faces 

 the task of organizing a campaign against a new and serious insect out- 

 break. Necessarily these difficulties and problems will vary widely 

 with the insect, the part of the country invaded, the host plant and 

 other factors, including the entomologist himself. Therefore that which 

 follows can be only the view of one entomologist, based on an exper- 

 ience necessarily limited and on contact with only relatively few 

 serious insects. That- which constitutes a difficulty in New Englantl 

 may turn out differently elsewhere, with another type of citizen to deal 

 with and with another man to do the ilealing. 



However, no matter where the work or who the worker, there is at 



