THE PEBBLE PROINIINENT. 71 



sometimes obliterated by a suffusion of the darker colour ; the 

 dark-brown first and second lines are often only visible towards 

 the front edge of the wings ; a blackish lunule or crescent forms, 

 in conjunction with the strongly curved outer line, the outline 

 of the characteristic pebble-like mark on the apical area of the 

 wings ; a pale saw-edged line, which is inwardly shaded with 

 dusky and intersected by black streaks on the veins, traverses 

 the pebble mark, but in the lighter coloured specimens this line 

 is not traceable. The female has browner hind wings than 

 the male. The moth is depicted on Plate 31, Fig. 2; and the 

 early stages on Plate 30, Figs, i, la, and i/;. 



The caterpillar, w4ien full grown, is pale ochreous grey, some- 

 times tinged with pink or purplish brown, or with yellowish, and 

 especially on the hind rings ; a yellow stripe along the back is 

 edged here and there with brownish ; the diffuse dusky line 

 along the area of the black margined spiracles is edged with 

 yellowish. It is occasionally found on poplar, but sallows and 

 willow are the more usual food plants, and it feeds upon these 

 in June and July and again in August and September. The 

 reddish brown chrysalis is enclosed in an earthen cocoon just 

 under the surface of the ground at the roots of tree or bush 

 upon which the caterpillar fed. The moth emerges in May and 

 June from chr)'salides of the previous year, and in August as a 

 second generation. Three broods in the year have been obtained 

 in confinement, but this is probably exceptional. 



Widely distributed throughout the British Isles, but seems to 

 have a preference for fens and marshy ground. It occurs all 

 over Central and Northern Europe, its range extends through 

 France to Spain, Italy, and Corsica, and it has been recorded 

 from Armenia and Amurland. 



