401 



(B) ADULT MOTHS. 



No experiments were successfully perlonned on adult moths. The 

 difficulties are great, and little work was attempted. Isely and Ackerman 

 ('23), however, have done some important work. The maximum ovi- 

 position at Bentonville, Ark., was on the second, third, and fourth days 

 after emergence, and did not occur except in very weak light. 



(C) EGGS AND LARVAE. 



Incubation Period. (Data by C. S. Spooner.) 



The only complete series of e.xperiments on incubation was that 

 carried on in unventiiated phials where the humidity ranged high, as 

 shown by precipitation on the glass walls at the time of many observa- 

 tions, and was arbitrarily taken to have averaged 95 per cent, though 

 there were no readings (Table XX). Data plotted (Fig. 23) for other 

 humidities are based on a limited number of readings. The alplia values 

 graphically estimated to be between 50° and 52° F., were approximately 

 the same as those calculated by Spooner. The deviation from the straight 

 line is fairly well indicated at the lower temperatures and also somewhat 

 uncertainly suggested in the neighborhood of 91° F. 



These velocities in Fig. 23 are based on an arbitrary total of 161 

 taken from Glenn's Table I. When placed on the pupal velocity chart, 

 they conform quite closely to the pupal velocities. Bringing them into 

 conformity with the pupal velocities does not shift them more than is to 

 be expected in smoothing. This conformity is also indicated by a com- 

 parison of Glenn's velocity (reciprocal) curves for incubation and pupal 

 development. A review of Glenn's data (shown in his Table I), by the 

 Von Oettingen method, gives 155 as the substitution-quotient when 

 51° F. is used as the alpha value. This makes the relative ])upal velocities 

 appro.ximately 10/17 of the relative egg velocities. When pupal velocities 

 are reckoned on the basis of 289 as the substitution-quotient, the egg 

 velocities should be reckoned on the basis of 172 for the constant-tem- 

 ]ierature experiments and IGO for the weather-variable temperatures. 

 This indicates that temperature variability has the same elTect on eggs 

 as on pupae. For variable-temperature experiments, 161 proved to be 

 the correct substitution-quotient. 



The 95 per cent humidity series calculated on 160 conforms very well 

 with the pupal velocities calculated on 270. The aberrant values at the 

 high temperatures are possibly due to too infrequent observation of 

 progress before the experiment began. Evidently, in these cases there 

 had been progress before the eggs were placed at experimental tempera- 

 tures. Since these abnormally high velocity values occurred in the 95 

 per cent set, their presence in the others, where in some cases the humidity 

 was in doubt, was not considered serious. The alpha value as determined 

 for the 95 set by the Von O. method is 52.1:°, and the substittuion-quotient 

 is 157. Experience with pupae indicates that the actual weather com- 

 binations of temperatures and humidities should give about 51.0°. as the 



