4ir 



larvae which pupate when put at S5° F. have passed the first phase of the 

 process. Larvae may pupate, when put under proper conditions, in November, 

 December, January, or February, or may fail to pupate as late as February. 

 Attention has already been called to the fact that this leaves no scientific basis 

 for a starting date, though January 1 is about average. However, to test the 

 relations of hibernating larvae still farther, a table showing the velocity value 

 for each degree Fahrenheit and each 5 per cent humidity was prepared from 

 Fig. 27. (These velocities were multiplied by 1.125, as before.) The temper- 

 ature above 43° F. and the corresponding humidity on even hours were tran- 

 scribed from hygro-thermograph records made by W. P. Flint near Springfield 

 in 191S. The beginning of development was assumed to be January 1. The 

 velocities were then written opposite the combined temperature and humidity. 



Air flow S mm. per stc, except TH. TI. TL,; these were 425. 109, 1.5, respectively. 



and the developmental units were summed to the date of the first pupation, 

 April 4. The developmental total, from January 1 to the first pupation, was 

 only 3312 instead of 4992 as in 1916. In Flint's Springfield records for 1918 

 there were no temperatures above 43° F. in January, and temperatures in sub- 

 sequent months were lower than in 1916. This makes evident that progress 

 at low temperatures takes place, or that January 1st was not the proper date 

 for beginning the calculation for this year. Both are probable inferences, and 

 this trial of the 191S data confirms the conclusion that we as yet have no means 

 of determining the date at which the larvae pass from the true dormant phase 

 to the "pre-pupal" phase. Accordingly, the table of velocities is omitted. The 

 velocities for average weather conditions as shown on the omitted chart, how- 



