276 



BRITISH LEPIDOPTERA. 



Comparison of N. microtheriella with the allied species. — 

 N. microtheriella belongs to that section of the genus in which there 

 is a single distinct pale fascia on each of the anterior wings, but the 

 fascia is not brilliantly metallic ; indeed, in this species, the fascia is 

 less shining than in any of the allied species, and it may by this 

 character alone be readily distinguished from N. vjnobilella , N. playi- 

 colella, N. tityrclla and N. malella, in all of which the fascia is 

 perceptibly shining. From N. argentipedella and N. acetosae it can be 

 distinguished by the more yellowish colour of the fascia, which is 

 more obliquely placed than in N. acetosae ; at the same time, 

 the size alone of N. anjentipedella would sufficiently distinguish it 

 from N. microtheriella, which is certainly the smallest lepidopterous 

 insect at present known (Stain ton). Fletcher notes that imagines of 

 N. poterii and N. filipendulae are quite as small as those of A T . micro- 

 theriella, whilst those of A r . acetosae aue much smaller. In a very 

 long series, Fletcher says that he has not a single N. acetosae as large 

 as his smallest specimen of N. microtheriella. 



Egg-laying. — The egg is deposited on the underside of a leaf of 

 nut or hornbeam, generally close to a rib, and almost entirely con- 

 cealed by the projection of the rib, and the short hairs to be found on 

 the back of the nut-leaf. It is rather more conspicuous when laid on 

 a leaf of hornbeam. 



Mine. — The larva commences its extremely narrow mine, proceeding 

 in a straight line close along a rib, and then turning off at a sharp 

 angle, when it meets another rib ; at times it crosses from one rib to 

 another, its path then being irregular and sinuous ; the excrement 

 forms a slender black line, which gradually becomes thicker, and 

 manifestly formed of individual grains ; it is occasionally interrupted 

 for short distances, but never loses its linear appearance ; the mine 

 appears on either side as a slender whitish-green streak. The larva 

 leaves the mine to pupate (Stainton). Frey writes : " Die Mine ist 

 ein sehr diinner, ausserordentlich langer Gang, in welchem eine sehr 

 feine Kothlinie die Seitenrander nicht erreicht. In dem Haselblatte 

 verlauft sie in unregelmassigen Windungen, oft mit einer zweiten und 

 dritten Mine sich kreuzend. In Hainbuchenblattern dagegen lauft 

 sie in starken, winkligen Biegungen, z. B. eine Strecke dem Bande 

 entlang, dann dicht neben einer Seitenrippe hin bis zur Mittelrippe, 

 von welcher sie sich dann plotzlich umbiegend wieder entfernen kann " 

 (Die Tineen, etc., p. 386). 



Larva. — Length 1^ lines ; very pale amber, with the dorsal vessel 

 dark green, giving, at first sight, the larva a greenish appearance, the 

 7 th and 8th abdominal segments reddish ; head pale reddish -brown, 

 the hinder part showing through the prothorax (Stainton). The larva 

 mines with the venter uppermost. 



Comparison of the larv^ of N. microtheriella and N. flos- 

 lactella. — Sie ist als Baupe und nach der Mine nicht ganz leicht von 

 N. floslactella zu trennen, mit der sie bei uns gleichzeitig in den 

 Blattern von Corylus avellana lebt, an deren Unterseite die Eier 

 beider Arten gelegt werden. Die Baupen beider sind blass gelb, aber 

 in veranderlichen Niiancen, mit griinem Darm, welcher dem ganzen 

 Leibe mehr oder weniger einen griinlichen Schein giebt ; im Allge- 

 meinen ist N. microtheriella als Baupe die blasser gefarbte, namentlich 

 ist ihr braunlicher Kopf, der manchmal fast farblos wasserhell sein 



