June, '22] glenn: codling moth and temperature 199 



Mr. T. H. Parks: I would like to know how Mr. Glenn arrived at 

 the conclusion that hiunidity and evaporation are negligible factors 

 in determining these results? With some other insects, we feel that 

 these factors are even greater than temperature. 



Mr. p. a. Glenn: The remark did not apply to the Hessian fly 

 or some other insects, but merely to the codling moth. 



Mr. T. H. Parks: How do you arrive at that conclusion? 



Mr. p. a. Glenn : It would take 15 minutes or more to explain that. 

 Humidity does have an effect if you use extreme humidity, but we don't 

 get extreme humidities over a long period of time under field condi- 

 tions. 



Mr. W. C. O'Kane: May I ask Mr. Glenn if, in speaking of day 

 degrees, you get at it by the average temperature for the day? 



Mr. P. A. Glenn: Yes. Above 50 or any degree we want. 



Mr. W. C. O'Kane: Suppose there were ten hours in a day and 

 in getting at the average you had a comparatively low temperature 

 at the beginning of the day, and then a long period of an optimum, 

 and then drop to a low temperature, as one example; while in another 

 day you had a comparatively high temperature and such a total as 

 would still give you the same average; could you disregard the hoirrly 

 temperatures during the day? 



Mr. p. a. Glenn: Yes, My method in making the average was from 

 a continuous record of the temperatures. I added the temperatures 

 for each hour and divided by twenty-four to get the average for the day. 



Mr. F. C. Bishopp: I was very much interested in this practical 

 appHcation of these laws of temperature, and I believe it is possible 

 to utilize them to a large extent in our economic procedure; but it 

 seems to me there is necessity for continued work over a good many 

 years in order to eliminate the various factors which creep in to in- 

 terfere with our theoretical laws or rules. 



In that connection I would like to ask Professor Glenn something 

 of the duration of his investigations. How long did they cover? 



Mr. p. a. Glenn: Three. years. 



Mr. F. C. Bishopp: As I believe you brought out, in the egg stage 

 for instance, reckoning the day as a unit, there is considerable error 

 when only a portion of a day is utilized in the transformation. 



Mr. p. a. Glenn: It is only by average of a large number that we 

 arrive at something near the correct results. If we take the day as 

 the unit, the actual length of the period may be nearly a day longer 

 or shorter than the observed time. 



President George A. Dean: The next paper is by Mr. Peterson. 



