PLEMTRIA] HYDRIOMENIDAE 205 



1. Cilia sharply barred to base . . .2. 



imperfectly or not barred . . .3. 



2. Markings black . . . .2. hastata. 



partly brown . . .3. tristata. 



3. Hindwings with grey median striae . . 4. 



without grey median striae . 1. bicolorata. 



4. Projection of median band double . 6. galiata. 



single . . .5. 



5. Postmedian band of hind wings clear white 4. rivata. 



divided by a grey 



stria . 5. sociata. 



1. P. bicolorata, Hufn. (rubiginata, F.) 20-25 mm. Fore- 

 wings white ; a brown basal patch, edge slightly curved ; median 

 band brown, usually interrupted or absent on lower half ; a 

 black discal spot ; fifth and sixth fasciae grey, darkest on a sub- 

 apical patch. Hindwings white ; a dark grey discal dot ; a grey 

 terminal band, including whitish subterminal line. A variety 

 occurs not uncommonly with the wings more or less wholly 

 suffused with grey. 



Britain to Ross, Ireland, common ; N. and C. Europe, WC. 

 and N. Asia ; 7. Larva slender, green ; dorsal line darker ; 

 spiracular greenish-yellow ; 13 with two points : on alder, black- 

 thorn, etc. ; 5, 6. 



2. P. hastata, L. 25-33 mm. Forewings ochreous-white, 

 markings black ; first two fasciae much curved, forming basal 

 patch ; median band somewhat white-marked, interrupted below 

 middle, posterior edge angulated in disc; traces of broken 

 strigulae on each side of it ; fifth and sixth fasciae rather broad, 

 fifth interrupted in middle ; cilia sharply barred. Hindwings 

 as forewings, but basal -f suffused with blackish-grey, subterminal 

 line partly obsolete. 



Britain to the Hebrides, S. Ireland, rather common ; N. and C. 

 Europe, N. Asia, N. America ; 6, 7. Larva deep brown or black ; 

 subdorsal line whitish, dull reddish, or absent ; a lateral series of 

 crescentic whitish or dull reddish marks : on birch and Myrica; 8. 



3. P. tristata, L. 22-23 mm. Forewings ochreous-whitish ; 

 first two fasciae curved, ochreous-fuscous, forming basal patch ; 

 median baud ochreous-brown striated with black, posterior edge 

 with angular median projection ; a series of dark fuscous dots 

 beyond this; a black discal spot, partially surrounded with 

 white ; fifth and sixth fasciae brown, fifth interrupted in middle; 

 cilia sharply barred. Hindwings as forewings, but base greyer, 

 discal spot less marked. 



