CONDITION OF LACHNEIS LANESTRIS DURING PUPAT. STATE. 123 



were also eleven pupa" with imagines more or less developed at 

 that date, of these two died, the rest emerged this spring. Of the 

 German cocoons noted, 45 were opened, and of these only two contained 

 undeveloped puptB, these two are undeveloped still. Of the 43 more 

 or less developed, all emerged except twelve, which were found to be 

 dead, bearing out my anticipation, that opening the cocoons would 

 prejudice the prospects of their inmates. The German cocoons left 

 untouched have provided 118 moths, eight dead chrysalids, and four 

 that are going over, being at present (April 1st) quite undeveloped. 

 The mortality in these unopened cocoons is much less than in the 

 opened ones, more than the present figures show, since dead ones were 

 eliminated last September from the opened ones, but not from these, 

 except by such rough test as weight in the hand afforded. The figures 

 themselves are respectively 27 per cent, for opened ones, and only 

 6 per cent, for unopened. The deaths resulted, I think, in most cases 

 from their being unable to emerge for want of a sufficient supply of 

 moisture. This conclusion is supported by the fact that the opened 

 ones presented also a much larger proportion of cripples, the wings 

 failing to complete their expansion, though no cause of this was 

 evident. It especially affected the hind margins and often only of the 

 hindwings. The twelve (I say eleven, by some inadvertence, vol. 

 xiii., p. 285) pupiB, of Mr. Russell's 1899 brood that were still im- 

 developed on August 14th, 1901, give a very interesting result. Mr. 

 Russell writes me that of these there emerged " March 18th, three ; 

 20th, one ; 27th, one ; 31st, one ; five out of the six were well formed 

 insects, and of the six remaining pupse, five are apparently alive, and 

 of the five, three show signs of development and two do not." Mr. 

 Russell kindly handed me these pupa^ on April 10th, when I got them 

 home I found three moths emerged, cripples, possibly naturally, more 

 likely from their confined quarters, one dead, and two ]nip* quite 

 undeveloped, but alive and healthy. From the sporadic emergence of 

 the six moths whilst Mr. Russell still had them, there is no doubt 

 these three moths were delaying their emergence till a little warmer 

 weather, which the circumstances of their transit persuaded them had 

 arrived. That these moths did not emerge at the same time as those 

 that were already developed last August conveys unfortunately no 

 lesson, as they were not kept together. This set of pupa> shows us, 

 however, that in pupjp already two years old, development of the imago 

 may be nearly complete by August 14th, or it may not have commenced, 

 although they ultimately emerge the following spring. In the German 

 pupcB none commenced any development after September 2nd. 



These results seem to corroborate the conclusions I came to pro- 

 visionally last year, and may be formulated somewhat as follows. A 

 specimen that is going to emerge in the following spring begins its 

 development within the pupa, at some time during the preceding 

 summer, and is quite developed before winter sets in. If it means to 

 remain over, no development occurs till the summer preceding the 

 emergence. Different broods vary immensely in the proportions of 

 early and late emergences, of some nearly all emerge the first spring 

 (97 per cent, in one of these lots), whilst in others nearly all go over. 

 There is probably some relation between a colder climate and more 

 frequent " going over," depending perhaps on the larvfe not pupating 

 early enough to get their development completed before winter. What 



