36 



it is evident that the <? would be equally subject to injury ; but for 

 the propagation of the race this would be of comparatively little 

 consequence ; from that standpoint it is much more essential that 

 he should retain his mobility in searching for the $ . 



Another theory advocated by our esteemed member, Dr. T. A. 

 Chapman (5), postulates that the dominating factor is the dormant 

 state of vegetation at the time of year when these moths are ovi- 

 positing. According to this investigator moths recognise the food- 

 plant suitable for their progeny, not by sight or touch, but by smell ; 

 he assumes that all vegetation during active growth emits charac- 

 teristic odours or scents, but that when dormant these emanations 

 are no longer given off, or at any rate to a very small degree, and 

 the winter moths are consequently unable to search them out. 

 Hence it is important that the female moths should not leave the 

 tree or shrub up which they have climbed on emerging from the 

 pupa. 



This theory does not account for the loss of her wings by the $ 

 Vapourer Moth, or for the yet further degeneration of the $ $ of the 

 family Paydiidd, in which cases some other factor must be looked 

 for ; neither does it explain why certain other winter-emerging 

 moths, such as Hitnera iiennaria, Pcecilocampa popiili, Krio(jaster 

 lanestru, etc., should have retained their wings in both sexes ; but 

 it does, I think, offer a very valuable suggestion as to the connection 

 between this phenomenon of aborted wings in the 2 sex and the 

 dormant state of vegetation in winter. That the l&rvse of the 

 moths in question are all very general feeders on trees and shrubs, 

 which frequently grow more or less densely upon the ground, would 

 seem to lend additional support to this theory. 



Certain TipulidcE that appear in winter are also apterous or 

 semi-apterous in the $ . In this country we have Tipula paiiana 

 which, though not truly a winter insect, appears in October, i.e., 

 very much later than any other of our Tipulida, while in New 

 Zealand several species appear in the winter months, the ? $ of 

 which, where known and probably in a good many species where 

 unknown, have aborted wings. 



In this connection mention may also be made of the little wing- 

 less Panorpid, Boreas liie;)iali>i. This case, however, differs from 

 that of the Moths and Tipuliila previously considered in that here 

 we find the wings aborted in both sexes. These insects, too, are 

 completely terrestrial, running and hopping on the ground over the 

 moss in which the larvae have developed, and probably afford a 



