February, '17] 



ENTOMOLOGISTS' DISCUSSIONS 



159 



Table LX — Per Cent op Infestation op Hessun Flt on April 1, 1915, before the Spring Brood Had Emerged 

 AND June 1, 1915, after the Spring Brood Had Emerged at Wellington and Newton 



Date of 

 Inspection 



Place 



Date of Seeding Period 



Sept. 

 16-17 



Sept. 

 21-23 



Sept. 

 27-30 



Oct. 

 5-7 



Oct. 

 12-17 



Oct. 

 19-21 



Wellington 

 Newton 







100.000 

 0.003 

 60.000 



Pbesident C. Gordon Hewitt: This paper is now open for dis- 

 cussion. 



Mr. T. J. Headlee: I wish to inquire of the speaker how we can 

 harmonize the data derived from the sowings at Columbus and Wooster, 

 Ohio, with the results he has gotton in Kansas since 1912. In five 

 out of a possible six years at Columbus and in seven out of a possible 

 nine years at Wooster, the date of sowing for maximum yield came 

 later than the date of fly-free sowing. 



Mr. G. a. Dean: I cannot explain this, but I believe that in order 

 to get your fly-free date and the date for maximum yield, you must 

 establish these local stations and carry on these experiments covering 

 a number of years. The first two or three years in Manhattan the 

 fly-free date was not far from the time for maximum yield. Then came 

 the years of Hessian fly outbreaks, increasing each year. For instance, 

 the damage in 1915 amounted to fully $16,000,000 followed next year 

 with a net loss totaling in the neighborhood of $15,000,000 or $16,000,- 

 000. It should be remembered that in Kansas we may get five broods 

 of the Hessian fly. For instance, we have the main fall brood, the 

 supplementary fall brood, the main spring brood, the second spring 

 brood, and the summer brood. In a state like Kansas, with a great 

 variation of climate and other conditions, I don't believe you can 

 figure out the conditions from another state, for instance, Ohio, where 

 they do not have such a great variety of climate and conditions as we 

 do in Kansas. 



Mr. a. D. Hopkins: This subject of the Hessian fly carries me 

 back to the West Virginia work, so that I am to be pardoned for di- 

 gressing from forest insects to talk about crop insects. Ever since that 

 work was done in West Virginia, beginning in 1887, I have continued 

 the study of the principle or law of altitude and latitude, and in recent 

 years the factor of longitude has been introduced, which clears up the 

 situation and enables us to indicate dates of periodical events like 



