i?o I.EPinOPTEKA. 



areas ahailfd only with smoky-black. One more jihase of 

 variation may be mentioned — that of size — which often in 

 the later brood ranges down very much smaller, occasionally 

 to little more than one half the full size of the species. 

 There are few species in which the great range of variation 

 is more diflicult to put into plain words without the risk of 

 becoming utterly tedious. 



On tin- wing in June and July, and as a second generation 

 in August and Se))tember; but this species is somewhat 

 erratic in this resi)ect, and there is hardly a month from 

 April to Octol)er in which it may not casually be taken. It 

 is not certain that tliere is not in some years a partial third 

 generation. 



Lai;v.\ nioderati'ly stout, slightly attenuated in front, sides 

 puckered ; head slightly paler than the ground colour, 

 streaked and dusted with black. \qt\ variable in colour — 

 blackish, dull green, greenisli-ochreous, or greenish-grey — 

 undersurface and sides beneath the spiracles conspicuously 

 pale ochreous or pale green, according to the ground colour. 

 On the back is a row, often indistinct, of pale ochreous, or 

 greenish diamond-shajied markings, each enclosing a black 

 spot : toward the hiniler end these pale spots unite and form 

 a band ; spiracular line interrupted, blackish ; below is a 

 black spot in each segment. There are two grey ventral 

 bauds and a black dash on the front of the base of the first 

 ])air of prolegs. (Chas. Fenn.) Occasionally a red dorsal 

 line is visible. 



•lune and •Inly, and a second generation in August and 

 September or even October : on horse-radish, wall-Hower, 

 cabbage, white arabis, Virginia stock, candytuft, scurvy- 

 grass, hedge-garlic and other cruciferous plants, also on 

 Tropcroluiii and other garden flowers, and occasionally upon 

 gooseberry and currant ; feeding at night and devouring the 

 whole leaf except the larger midribs ; remaining usually on 

 the underside of the leaf. In re]xise it raises itself in the form 



