328 BRITISH LEPIDOPTERA. 



sind diese Flecke kleiner, gelblicher, schiirfer. Die iiussersten um 

 die Spitze herum auf den Franzen liegenden Schuppen sind lang, und 

 ihre dunkeln Enden bilden einen dunkeln Ring um die Spitze hinter 

 einem lichteren Ringe. Die Franzen dahinter sind hellgrau, kaum 

 ein wenig gelblich schillernd. Hinterfltigel heller grau, als die 

 einfarbige Unterseite der Vorderfiiigel, deren Franzen so hell sind, 

 wie auf der Oberseite. Das Weibchen (mein einzelnes Exemplar) 

 ist auf den Vorderfliigeln dunkler, weniger gliinzend und die Gegen- 

 flecke gelblich und scharfer umgrenzt (Linnaea Entomoloyica, iii., 

 pp. 320-322). 



IMAGO. Head ferruginous. Anterior wings 6-7 mm. ; scales 

 blackish, paler at their bases ; bluish-black towards the apex ; two 

 opposite whitish spots near middle .^of wing, one (small) on costa, 

 another (larger) on inner margin ; cilia grey, long, with silvery white 

 tips. Posterior wings pale grey, the cilia paler. 



COMPARISON OF N. ARGYROPEZA WITH N. SUBAPICELLA. The imago 

 of N. aryyropeza, Zell. (= apicella, Sta.), has the costal and dorsal spots 

 exactly opposite. The imago of N. subapicella, Sta. (= aryyropeza, 

 Sta.) has the costal spot anterior to the dorsal spot (i.e., the costal spot 

 is nearer to the base of the wing than in the former) (Stainton). 



EGG-LAYING. The egg is laid upon the stalk of an aspen leaf, "about 

 a quarter of an inch from its junction with the leaf " (Vaughan) ; " at 

 the end of the leaf -stalk " (Heyden). Nolcken has found as many as 

 four eggs on one petiole, but never more than two mines in one leaf. 



MINE. A small swelling is formed where the young larva bores 

 into the petiole at the foot of an aspen leaf. The larva then mines up the 

 petiole to the foot of the leaf, and forms a wedge-shaped blotch at the 

 base of the leaf. Vaughan notes that the young larva, after pene- 

 trating the stem, enters the leaf at the midrib, and mines the upper 

 cuticle, rarely passing through a rib, but completely devouring all the 

 substance between the middle and one side rib, thus forming a wedge- 

 shaped mine with the excrement irregularly scattered. Heyden says 

 that the portion of the leaf-stalk mined is flattened sideways, and 

 tolerably thick, the mine forming an elongate black- brown blotch, that 

 widens anteriorly, and is sometimes five lines long, and placed between 

 the edge of the leaf and first lateral rib, or between the latter and the 

 midrib. Nolcken says that the mine is always between two ribs, and 

 bounded with a curve on the outer edge, the frass being arranged 

 irregularly, and collected in little heaps. Heyden notes that there is 

 often a mine on either side of the midrib. Wood says that " to see an 

 aspen tree with nearly every leaf of a pure yellow, save for a bold 

 splash of vivid green striking across from stalk to margin, is an 

 extraordinary sight, and one that can scarcely fail to attract attention." 

 Sorhagen notes that " the black frass is deposited in the mine in two 

 parallel streaks along each rib, the small empty space between which 

 looks like a continuation of the midrib." 



LARVA. Length 2 lines. Pale amber, the dorsal vessel greenish 

 or brownish-green, head pale brown, darker at the side, prothorax 

 greyish above, posteriorly with two reddish-brown subcutaneous 

 patches, forming a horseshoe-like mark. On the underside of the 

 prothorax is a dark brown subcutaneous patch, posteriorly black ; 

 some wedge-shaped yellowish -brown marks are visible on the under- 

 side of the third, fourth, fifth and twelfth segments (Stainton), 



