June, '22] Glenn : codling moth and temperature 197 



Owing to the comparatively small mimber of observations used in 

 making the above averages the results are not very consistent. They 

 show an average acciunulation of 1027 day-degrees for the complete 

 life cycle; that is, from egg to egg, larva to larva, etc. In making 

 the observations no doubt the first individuals were not noted in every 

 case, consequently 1027 day-degrees is probably greater than the actual 

 ntimber that acamiulate between the time of appearance of the first 

 individuals of one brood and the first individuals of the next brood. 



The minimiim accumulation of effective day-degrees during the de- 

 velopment period found by adding the minimum for the egg, the 

 larva, and the pupa was 939, the minimum, found by treating the 

 entire development period as one period was 950. To get the minimum 

 accumulation for the complete life cycle, we add 50 day-degrees to each 

 of the above to allow for the accumulation during the time which elapses 

 between the date of emergence of the moth and the date of egg 

 deposition. This gives 989 and 1000 respectively as the minimum ac- 

 cimiulations for the complete cycle. The average of these three min- 

 imimis, 989, 1000 and 1027 is 1005. Therefore, after the first individuals 

 of one brood appear we may expect the first individuals of the next 

 brood to appear when 1000 effective day-degrees have accumulated. 

 An equitable distribution of these 1000 effective day-degrees between 

 egg, larva, pupa, and the interval between the emergence of the adult 

 and the deposition of the first eggs would be 158, 532, 260, and 50 

 respectively. Now if we revise table 4 so as to make it consistent 

 with the above distribution of effective day-degrees, we have the ap- 

 proximate number of effective day-degrees which will have accimiulated 

 at the time of the appearance of the first individuals of each of the 

 broods during the season. These are shown in table 5. 



Table 5. — Approximate Number of Effective Day-Degrees witiCH will 

 HAVE Accumulated when the First Individuals of Each Brood Appear. 



Effective day-degrees 



1st pupae, hibernating generation 82 



1st adults, .. w 342 



1st eggs, first " 392 



1st larvae " " 550 



1st pupae " " 1082 



1st adults " " 1342 



1st eggs, second " 1392 



1st larvae, " " 1550 



1st pupae, " " 2082 



1st adults " " 2342 



1st eggs, third " 2392 



1st larvae, " " 2550 



