262 . BRITISH LEPIDOPTERA. 



thus frequently going up one side of the leaf, round the apex and 

 down the other side ; the excrement is, during the first half of the 

 mine dark brown, but in the latter half it is nearly black. When 

 the larva is nearly full grown, the excrement does not fill up the 

 whole width of the mine (Stain ton). Frey writes : "Die Mine wird 

 in eigenthiimlicher Art gewohnlich (aber doch ausnahmelos*) bald 

 gegen den Blattrand gefiihrt, urn hier jeder Kriimmung desselben zu 

 folgen und so zum stark gezackten Gange zu werden, welcher von 

 breiter, braunschwarzer Kothreihe gefiillt wird" (Die Tineen, etc., 

 p. 395). 



Larva. — Length 2 lines ; pale amber-yellow ; the head pale brown, 

 and the hinder lobe of the head showing through the upper surface of 

 the prothorax as a pale brown spot (Stain ton). The larva mines 

 with the dorsum uppermost (Wood). Nolcken describes the larva as 

 " pale (whitish) yellow, with pale reddish-brown head, the intestinal 

 canal brownish, and faintly visible through the skin, the venter being 

 marked with a series of lozenge-spots." 



Cocoon. — The cocoons average 3*1 mm. in length and 1-9 mm. in 

 width. The cocoon is dark greenish-grey, sometimes tinged with 

 brown. It forms, roughly, an oval in outline, squared towards its 

 narrower end. The wider end is somewhat flattened on its margin, 

 forming a considerable flange, rising rather rapidly at some distance 

 within the border to the central domed area. The latter portion of the 

 cocoon is rather smooth, but the flanged portion is well-supplied with 

 flossy whitish silken fibres, by which thecocoon is attached to some object. 

 Two of the six cocoons examined have an irregular fracture (probably not 

 for escape of pupa) at the narrower but thicker end. The flat base sug- 

 gests that it is spun on a leaf, etc. [Described June 5th, 1898, under a 

 two-thirds lens, from cocoons sent by Dr. Wood.] Some cocoons sent by 

 Fletcher are almost green-black in colour, and average 3 - 3 mm. in length, 

 and 2*1 mm. in width. Stainton observes that the larva usually leaves the 

 mine to spin its cocoon, and he has noticed that in those cases in 

 which the cocoon is formed inside the mine, the imago is never bred, 

 and hence he supposes that they only thus construct it when weak or 

 diseased. He describes the cocoon as " dark greenish-brown in colour, 

 the pupa protruding its anterior segments before emergence." Hind 

 gives the colour of the cocoon as " green." Nolcken says the fresh 

 cocoon is greenish-brown, with a paler greenish rim, sometimes 

 blackish-green, or dirty leaf -green. 



Food-plant. — Ulmus campestris. 



Time of appearance.— The insect is double-brooded, appearing in 

 May and again in August ; the larvae of these broods may be found in 

 September, October and July respectively. The imago was taken 

 on May 9th, 1847, at Beckenham (Bedell), and on April 21st, 1896, 

 at Aberfoyle, where it was beaten out from amongst heather (Evans). 

 Mines were found commonly on elm at Lewisham, October 8th, 1891, 

 October 3rd, 1892 (Bower) ; whilst Shield obtained larvae in elm leaves 

 in October, 1853, at Howth. On the other hand, at Haldon, many 

 larvae had left the mines on September 21st, 1865 (Jordan). Stainton 

 captured imagines May 17th, 1851, April 17th, 1853, at Lewisham ; 



*In den grossen Blattern junger Baume kann, wie ich mehrfach sah, die 

 Mine dicht an der Medianrippe beginnen, dann neben einer Seitenrippe nach dem 

 Aussenrand gehen und in gestreckteni Verlaufs enden, ehe sie jenen erreicht hat. 



