THE DARK SWORD GRASS. 209 



of the two last, sometimes both, may occasionally disappear. 

 Not infrequently the reniform is connected with the orbicular by 

 a black streak from the former ; more rarely the claviform is 

 much widened and lengthened, and almost united with a dusky 

 cloud above it {w2iY. plaga^ Steph.). This species is sometimes 

 mistaken for A. corticea^ but apart from the shorter teeth of the 

 male antennas, the present species has a distinct, and often 

 conspicuous, black mark on the front of the thorax. 



The caterpillar is brownish with darker pear-shaped marks 

 on the back ; lines dark edged ; spiracles black and of large 

 size. Head pale marked with brown. It feeds from July to 

 May on various low herbage, including lettuce, chickweed, 

 plantain, and goose-foot ; also turnips. 



The moth flies in June and July (sometimes in September), 

 and is generally commoh ; but in Scotland it does not appear 

 to extend north of Moray and Argyle. 



The Dark Sword Grass {AgroHs ypsilon). 



The sexes of this moth are represented on Plate 104, Figs. 

 7 ^ and 8 $ . In occasional specimens of the male the ground 

 colour of the fore wings is rather pale brown ; otherwise there 

 is little variation to note. The caterpillar feeds from April to July 

 on roots and leaves of cabbage, lettuce, goose-foot, and many 

 low plants ; also on swedes, mangold wurzel, etc. It is purplish 

 or bronzy brown above and somewhat greener on the sides ; 

 the usual spots are blackish and the lines greyish edged with 

 darker. Head black with two white spots. The moth is on 

 the wing from July to September, and as it is sometimes seen 

 in April and May and earlier, it is said to have probably 

 hibernated. Possibly, however, such early specimens, found 

 at least once in February, are immigrants. Sometimes the 

 species is common and at others rare. It has occurred at one 

 time or other almost everywhere in the British Isles, but it 

 seems to be most regularly obtained in England and in Ireland. 



P 



