844 BRITISH LEPIDOPTERA. 



? Decentella, H.-Sch., " Sys. Bearb.," v., p. 358 (1855) [= ? 2nd gen., tcste, Frey, 

 " Lep. der Sch.," p. 425 (1880)]. 



ORIGINAL DESCRIPTION. Sericopeza, Z. Grosse der Ojwxt. xjxu-ti- 

 foliella, also grosser als die 4 vorigen Arten (N. 1iemargyrdla,aryyropeza t 

 argentipedella, leutniscella) ; die Vorderfliigel zugerundet, etwas gliin- 

 zend, grob schwarzbeschuppt mit violetter Spitze ; eine Binde vor und 

 2Gegenlieckebinterder Mittegelblichweiss ; die Kopfhaare schwarz oder 

 rostgelb ; die Augendeckel gelblich. Viele Exemplare ira Tbiergarten 

 bei Berlin an Baumstiimmen im Mai gefangen (Zeller, his, 1839, p. 

 215). Zeller afterwards diagnosed (Linn. {'Int., iii., p. 325) the 

 species as follows : " Alis anterioribus fuscis, basi, fascia curva media 

 niaculisque duabus oppositis posticis pallidis ; capillis ferrugineis, 

 concbula albida, antennis fuscescentibus." 



IMAGO. Head reddish-orange. Anterior wings G-8 mm. ; blackish ; 

 an oblique whitish fascia before the middle ; two opposite yellowish- 

 white spots beyond the middle ; cilia very pale yellowish-grey. Posterior 

 wings pale grey, with paler cilia. 



VARIATION. Frey considers that N. decentella, H.-Sch., may be a 

 small summer generation of this species. Herrich-Schaffer's diagnosis 

 reads as follows: " N. decentella, m. Suppl., 815. (^ericnpc-a, Sta., 

 eher hieher.) Capillis nigerrimis, thorace omnino fiavido." Herrich- 

 Schaffer then gives a detailed description in German, and notes the 

 species as coming from Frankfort-on-the-Main (Miihlig) and England, 

 in June. 



EGG-LAYING. The eggs are laid on the keys. Warren watched a 

 female ovipositing in the middle of September, 1881, on the keys that 

 were then green. 



MINE. The mine usually commences near the middle of the wing 

 of a fruit, and passes towards the stalk, winding much before the 

 cavity containing the fruit is reached. It is most conspicuous between 

 the two fruit wings. When the larva has reached the space containing 

 the seed, it lives here for a time without mining, and a large heap of 

 excrement is collected therein. The terminal part of the mine forms 

 a comparatively large empty space, where, the larva emerges from the 

 key (Woeke). Goureau notes that the larva feeds in the seeds of 

 Acer platai widen, and causes the samaras or keys to fall before the 

 seeds are perfectly ripe, owing to the flow of sap being checked. The 

 affected portion of the keys becomes blackish. 



LARVA. When full-grown, 4 mm. long ; pale amber-yellow in 

 colour, transparent and slightly glossy ; the alimentary canal slightly 

 green ; the head of the same pale yellow tint as the body, with two 

 very fine brown lines converging to the front and with very fine brown 

 dusting, the mouth brown ; the posterior part of the body slightly 

 darker (Wocke). 



COCOON. When fresh the cocoon is very bright yellow and very 

 neatly spun, but when discoloured it becomes dirty- white or pinkish. 

 In April, the hybernated larvre spin their cocoons on the tree-trunks 

 (Wocke). On June 13th, 1859, Goureau detected a nearly circular 

 cocoon on a fallen key of Acer platanoides, and from other keys (that 

 had fallen before the seeds were perfectly ripe) collected, four or five 

 larvae emerged, and spun flat white or whitish-rosy cocoons on the keys. 

 In May, 1883, Warren found freshly-spun cocoons, both on the new, 

 half-developed keys, and on the fresh young leaves of Acer campestris, 



