88 Mr. Merrifield's incidental observations 



to 29th August. The moths emerged from 17th August 

 to 13th September, having been gently forced (about 

 65°— 70") from 6th September, after which date 7 or 8 

 of them emerged. x\s nearly as I can tell, the larval 

 period averaged about 64, the pupal about 31 days. 

 There were 16 males and 9 females, none crippled. 

 The larval 2)eriod can onl}^ be roughly estimated, as the 

 sj)un-up ones were only taken when the sleeve was 

 examined at considerable mtervals. The first 5 were 

 found 26th July, the next 18 on the 9th August, and as 

 taken they were transferred to a tray indoors, which 

 stood far from the window ; I remember that on these 

 occasions there were several that had only just begun 

 to spin up. At this time (9th August) there were 

 5 larvjTS feeding, and they were transferred to a bottle 

 indoors; 2 of them spun upon the 10th August, and 

 one each on the 25th and 29th August ; these 4 were 

 also transferred to the tray as they spun up. 



The sleeved larvae were therefore exposed during over 

 60 days on the average to the cold summer, the 

 temperature of which, as taken about 8 a.m., averaged 

 barely 57^ up to 9th August, when most had spun up. 

 I do not think the temperature during this period ever 

 reached 70° at that hour, and I have no doubt it was at 

 night on one or two occasions near 40". The tempera- 

 ture in the room where the pup^e stood, taken about 

 8 a.m., averaged about 66° during the time they were 

 there, i. e., from 24th July to 6th September (often 

 higher, especially during the afternoon, when it must 

 frequently have passed 70°), and rarely much lower. 

 I should doubt if it ever fell below 58°, and that only on 

 rare and brief occasions. I think it may therefore be 

 taken that the pupae of fully a quarter of the 25 moths 

 which emerged passed their whole existence as pupae at 

 an average temperature of 66° or upwards, and that 

 nearly all of them passed much the greater portion of 

 their existence at that temperature. The larvte and 

 pupge of those described as " bottled," the moths from 

 which in colour and markings are not far short of the 

 sleeved, were never at a lower temperature than that of 

 the room, which, however, averaged several degrees 

 lower for the 6 or 7 weeks preceding 24th July than 

 afterwards. 



If the great difference between the forced and the 



