274 . BRITISH LEPIDOPTERA. 



beginnt als ein sehr feiner, von der braunschwarzen Kothreihe ganz 

 erfullter Gang, welcher dann plotzlich in einen unbestiramt rundlichen, 

 oft stark ausgebuchteten, griinlich weissen Fleck iibergeht, worin die 

 Excremente einen unregelmassigen Haufen bilden." Sorhagen writes : 

 " Die Fleckenmine entwickelt sich plotzlich aus einer feinen langen 

 Gangmine, die mit schwarzem Kothe ganz gefiillt ist, wahrend sie 

 selbst griinlichweiss ist und den Koth in einem Haufen in der Mitte 

 hat. Oft bilden 2 Raupen eine gemeinschaftliche grossere Blatter mit 

 2 Kothhaufchen." 



Larva. — Length 2 lines. Pale amber, shining, transparent, dorsal 

 vessel slightly greener ; head small, reddish-brown, working up under 

 the prothorax, through the upper surface of which the posterior part 

 can be distinctly seen (Stainton). Frey writes : "Die Larve in den 

 beiden Generationen, der sommerlichen (bei uns schon in der zweiten 

 Junihalfte) und der herbstlichen, bis tief in den Oktober hinein an 

 Schlehen (Prunus sp'mosa) und auch an Zwetschenbaumen (Primus 

 domestica). Sie ist blassgelb mit dunkler durchschimmerndem Darm- 

 kanale und einem rothlich-braunen Kopfchen." 



Comparison of the larva and mine of N. plagicolella with 

 those of N. prunetorum. — The larva of N. plai/icoldla is yellow, and 

 makes a clear whitish blotch, preceded by a slender gallery. The 

 larva of N. prunetorum is green, and its mine is coiled like a watch- 

 spring, afterwards extending round the edge of the leaf ; the " frass " 

 fills up the gallery, and makes it light brown (Threlfall). 



Cocoon. — The cocoons (7) average 3 mm. in length and 1-75 mm. 

 in width, forming a long oblong-oval. There is a wide flange round 

 three sides of the cocoon, one of the long sides being, however, almost 

 devoid of it. This side rises almost directly to the highest point of the 

 domed surface which surmounts the flange, the elevation being more 

 gradual on the other sides. The domed area is comparatively smooth, 

 with a few fine, slender, irregular reticulations, rather darker than the 

 ground-colour ; the latter is ochreous-brown, inclining to yellowish. 

 There is a considerable amount of loose flossy silk of the same colour 

 as the silk of the cocoon scattered over the flange, a similar, but much 

 thinner, coating covering the domed surface. [Described June 16th, 

 1898, under a two-thirds lens, from cocoons sent by Dr. Wood.] 

 Stainton describes the cocoon as " brown, rather flat, especially at the 

 edges, and in shape not far from circular ; the pupa protrudes its 

 anterior segments through the end of the cocoon previous to the 

 escape of the imago." Frey writes : " Der lebhaft rothbraune Cocon 

 ist glatt, rundlich und sehr stark abgeflacht." 



Food-plants. — Primus spinosa and P. domestica. Fletcher adds : 

 Abundant in sloe, in garden plums, in Primus myrobalana, P. divaricata 

 var. pissardii and P. jdponica (sinensis). 



Time of appearance. — There are two broods, the imagines appear- 

 ing in May, June and August, the larva? of these feeding respectively 

 in September-October, and July-August. Stainton bred imagines, 

 from Lewisham, on July 12th-29th, 1852, from larvai found at the 

 end of June, 1852; July 28th-August 21st, 1853; April 10th-30th, 1854; 

 May 2nd-llth, 1855 ; also from larvae taken at Cheshunt, April 30th, 

 1854 ; imagines were caught at Dartford, June 22nd, 1852, and at 

 Lewisham, flying along hedges, from 5.30 a.m. to 6.30 a.m., on May 

 16th, 1852. Mines were found in sloe, on October 5th, 1891, at 



