THE CANADIAN ENTOMOLOGIST. 47 



any other hibernating butterfly. Nor have I found any evidence of excep- 

 tionally long life, or of the old hibernating females being about all summer, 

 laying eggs with their progeny. And of course they do not witness the 

 decay of the food plant, for the milk-weed does not die early, but lasts 

 till frost in October, and will stand pretty severe frost. On 28th Sept., I 

 wrote Mr. Edwards: "We have had two pretty heavy frosts within a 

 week, but the Archippus larva? and more than half the milk-weeds are 

 fresh and vigorous." On 30th Sept., I wrote.: " Found the 34th larva 

 this morning. Frosts have not been severe enough to kill larvae. Most 

 of the 34 have been on young milk-weeds, after the first mowing. Now 

 the fields have been mowed the second time, and this explains why the 

 late brood of the larva and imago may be scarce in some parts of N. 

 England." 



On 56th Oct., I wrote : " I now have four pupae, of which one should 

 give imago to-morrow, and three will wait a week. The pupal period in 

 October, the pupae being kept in a cool room, is about three weeks. In 

 September, it was of about 15 days duration. Larvae taken 2nd Sept., 

 pupated 9th to 12th Sept., and the imagos came out 25th to 30th Sept." 



I wrote 29th Oct. : " The one pupa has given imago." On 4th Nov., 

 I wrote : " Another imago out this morning, a fine female. I have two 

 pupae left, and send you them by this mail." 



It is plain to be seen why imagos are rare in the fall, and therefore 

 more rare in spring, for there must be more or less loss of them in the 

 winter. In New England quite generally the fields are mowed the second 

 time, and that very late. Thus, while on Sept. 9th were taken nine larvae 

 in a field near my house from a group of milk weeds, before larvae of the 

 same generation could have completed their stages, all the food plants 

 were cut down. So myriads of larvae must be annually destroyed in New 

 England. 



I saw wild Archippus flying on the 5th of Oct., again on 13th, in 

 both cases after some frosts, as I have before mentioned. Of course these 

 late flying ones are the hibernators, and liable to be caught any day at 

 that season by cold that would compel them to seek hiding places or else 

 become torpid out of doors. 



