•44 THE entomologist's RECORb. 



useless but a strong temptation to, or at least risk of, great disaster by 

 the female Hying away from this most satisfactory position. 



We see the transition to Xotolojihus in, say , L'ltrtJutria dixpar, where 

 the $ almost always lays a large batch of eggs close to her cocoon and 

 before flying. Similar conditions are possibly dominant in the case of 

 other apterous moths, of which I know little, such as some Arctiids, since 

 in many species of moths, of which Airtia caja is one, the female usually 

 lays a considerable number of eggs before making any serious use of 

 her wings. If this first batch made its way in the world distinctly 

 better than later ones, then A. caja would have taken the first step to 

 having an apterous female. 



Will these considerations help us to understand why the "winter" 

 moths are apterous "? Clearly, the explanation is not applicable as it 

 stands, since all these apterous females of the "winter" moths, though 

 wingless, have quite exaggerated powers of locomotion afoot, a con- 

 dition precisely contrary to that which obtains in other apterous 

 females, which have often lost their legs, as well as their wings, and, 

 at any rate, as in Xotoloj>ht(s antiijua, make very little use of them. In 

 Hetero<jipm the loss of pedestrian power has been very specially engi- 

 neered, in view of the necessity of the female moth preserving an 

 exact relationship with her pupa-case, vi::., the imaginal legs consist 

 merely of an organic connection with the pupa-case, which is never 

 severed. 



Nevertheless, the explanation seems to me to be in very similar ob- 

 jects having to be attained, but under very different conditions. This 

 explanation, when arrived at, seemed to me so obvious that I think it 

 very likely it has been arrived at before, but if so I do not remember 

 to have met with it. The labour of searching out references, if any 

 are available, seems more than the subject is worth, especially as, in 

 ■ case the matter is not new, an independent suggestion will be con- 

 firmatory. It will probably, also, be new to many as it is to me. 



What are the facts ? These are tolerably well known ; yet it may 

 be better to recapitulate them. Confining our view to British species 

 of moths which appear in the winter months, we have fifteen species 

 whose females are apterous. How many we have whose females are 

 not apterous is a more difficult matter. Species that hibernate are, 

 of course, not in question, but the others gTade so regularly into late 

 autumn and early spring species that it is difficult to say which should 

 and which should not be included. The following, at any rate, need 

 to be considered: — Avijihidasy.s strataria, lUmera pcnnaria, Chciniato- 

 jiliila tortricella {T, liyeinana), Sciiiioscopis acellaiiella, Lacluieis lanestris, 

 Poecilucainpa poptili, Aateroscojins sphinx, A. nnhecnldsa and Ptilophora 

 plnmiijera. There may be one or two others 1 have not thought of or 

 erroneously excluded. These are nine species to compare with fifteen 

 that are apterous — an overwhelming proportion when we recollect 

 there are no apterous summer species outside the special cases I have 

 noted above. Of these nine some are, perhaps, rather early spring or 

 late autumn than really Avinter, or, we may say, are in a transition 

 state from one to the other. A. strataria, II . pennaria, L. lanestris, and S. 

 urdlandla are, perhaps, spring species ; A.t^pliiii.r (lassinea) is probably an 

 autumn one. Several of them, also, as befitting transition species, have 

 some difficulty in fully developing the female wings, especially the hind- 

 wings, as A. strataria and //. pi nnaria. 



