( xcii ) 



Tlieclas, and the Geometric! moth Ennomos angularia, pass 

 the winter as eggs, and by Scoliopteryx libatrix, and many 

 other moths which hibernate in the winged stage. So the cohl- 

 weather moths of autumn, winter, and early spring, the four 

 common Hybernias and Cheimatobia, Lrumata and Phigalia 

 pedaria, rapidly run through the stage of larva in about two 

 months, and lie all through the greater part of the year, 

 including its hottest period, before they emerge as moths. 



Cold required, to mature wittier pupae. 



A continuation by artificial means of heat not only fails to 

 accelerate but often retards or kills, and in some cases throws 

 the emergence over to another year, so that in these cases 

 cold is necessary to accelerate or cause maturity. Four Thais 

 polyxena, a year-lived spring butterfly of Southern Europe, were 

 placed by me at 8CT F. (27° C.) on each of the following dates, 

 12th November and 31st December. All were dead by 14th 

 March except one of the first lot, which emerged a cripple 

 28th December. Of four placed there on 14th March and 

 two at 92° F. (33° C.) on 25th March, all emerged ; of some 

 that were left out of doors all, or nearly all, emerged 16th to 

 30th May. Ten Rumia luteolata placed by me on the 18th 

 October at 80° F. (27° C.) were all dead by March ; ten placed 

 there on the 20th March all died except three, which emerged 

 from the 4th April to the 2nd May, one being a cripple; of 

 twenty placed there on the 2nd May, twelve emerged between 

 the 6th and 22nd May ; many left out of doors emerged be- 

 tween the 17th and 31st May, and a few later. Of twenty- 

 five Hybernia marginaria placed on the 19th October at the 

 more moderate temperature of 63°-70° F. (18°-21° C), 

 not one had emerged by the 1st March, by which time many 

 at the temperature of a cold room had emerged. Of seventy- 

 five C. brumata brought indoors when the weather began to be 

 cold in October, and on the 2nd November placed at 63°- 

 70° F. (17°-21° C), not one had emerged by the 12th 

 January, when many at the ordinary temperature had 

 emerged ; some of them had been killed by the warmth indoors. 



