172 feEiTisii lEPibop^ERA* 



fasciella, X. ruficapitella, and others. The larvse of N. aceris must 

 have a very short duration of life, even in autumn, for, although 

 the mines are not scarce on some maple trees and maple bushes on 

 our promenades here, neither in summer nor autumn have I yet 

 succeeded in finding a mine still tenanted, although I have searched 

 the said trees and bushes almost daily." 



Warren mentions a disease to which Nepticulid larvae are sometimes 

 subject. He writes : " This disease would seem to commence with a 

 discoloration of the dorsal vessel alone, the larva ceases to feed, and 

 dies in situ, after which the whole body becomes dark. This mortality 

 is not attributable to the attacks of ichneumons, but is possibly owing 

 to premature wet and cold weather in the autumn ; the larvre try to 

 feed up too fast, and pay the penalty." Durrant, on the other hand, 

 associates this, or a similar disease, with exposure to excessive heat, 

 which also appears to be disastrous. 



The nature of the mine offers excellent characters for the 

 differentiation of many species, and Wood has made himself so dis- 

 tinctly the authority on this part of the subject in Britain, that we 

 have drawn largely on his papers, not only for the detailed descrip- 

 tions that follow, but for much of the information that may be found 

 scattered throughout the preceding and succeeding paragraphs. 



The mines of some species are not difficult of detection, but a 

 certain amount of training is necessary to find those of others, e.g., 

 Stainton writes (Zoologist, 1853, p. 3955) as follows: "About the 

 middle of October last (1852), I paid a visit one morning to a bush of 

 Rhanmus catharticus, on which I expected to find the autumnal brood 

 of the larvae of N. catharticella. To my surprise, on carefully ex- 

 amining the bush, I could not find a single larva ; however, I was so 

 satisfied that they must be there, that I continued to look, and as my 

 eyes gradually became more accustomed to the indications of those 

 objects for which I was searching, I found that, so far from there 

 being no larvas before me, they were really there in hundreds." 



The position of the mine is of comparatively little importance, 

 although even this is diagnostic of certain species. Thus, amine at the 

 foot. of an aspen leaf is that of N. argyropeza (apicella) ; the small blotch 

 projecting from the side of the midrib into the lamina of a willow-leaf 

 betokens A r . intimella, whilst N. subbimaculella is almost invariably 

 found in one of the angles of the midrib of an oak-leaf. The mines of 

 N. regiella and N. ignobilella are found on the margins of a hawthorn 

 leaf, and a mine towards the centre is always suspicious. N. turicella 

 (titgrella, coll.) usually keeps to the narrow space marked off by two 

 adjacent veins of a leaf, and so, can generally be distinguished at once 

 from N. bamlella (fulgens, coll.), which occupies more than one inter- 

 space. Mines are always placed on the upper side of a leaf, even when the 

 eggs are laid below, the newly-hatched larva boring at once towards the 

 upper surface, as if to get to the brighter and sunnier side. 



The characters of the mine are of much more importance than its 

 position in the determination of species. The mine may be a gallery 

 (X. alnetella), a blotch (N. argentipedella), or a compound of the two (N. 

 auguli fasciella). But the blotches are really of a composite nature 

 starting first as a gallery of varying size, sometimes long and hair-like, at 



* JUntom. Mo. Mag., vol. xxix., pp. 197 et ueq. 



