488 BRITISH LEPIDOPTERA. 



time taken may be increased by half-a-day to two days, according to 

 temperature, and the change is never so thorough as in warm 

 weather. In cold weather (say night temperature of 5 °C. to 8°C. 

 with cold dull days, or with a mistral) the orange colour becomes 

 greenish and pale, and the dark dorsum smoky greyish-black, not 

 intensely black (Powell). 



[Page 254.] Ontogeny of larva. — First instar: The larva 

 is slender, pale green or yellowish-green in colour ; the caudal 

 horn black, very long and thin. [The larva in this and the 

 next two stages, when not feeding, lies along the midrib at the 

 back of a leaf, the caudal horn in the 1st and 2nd stages 

 being laid flat along the midrib behind the larva when the 

 latter is at rest, but held in an almost upright position when 

 the larva is moving.] There is a faint indication of the blue 

 ocellated spot on each side of the metathorax even in the first 

 stage. Second instar ; The white-centred, blue metathoracic ocellated 

 spots are rather more distinct, and the yellowish-white subdorsal line 

 which runs down the abdominal segments to the base of the 

 caudal horn, well above the spiracles on each side of the body, 

 is visible. The horn is also shorter in proportion to the length 

 of the larva. Ihird instar: Just after the second moult the 

 length is 32mm. not including the horn. Caudal horn 7 -5mm. 

 Head green, smooth. Thoracic segments telescopic and tapering 

 towards the head. Body green, rather milky-green on dorsal 

 surface. The metathorax has on each side a small blue, white- 

 pupilled spot, behind which commences, very faintly, the creamy 

 subdorsal line which runs down to the base of the horn where 

 it nearly joins the corresponding line from the other side of the 

 body; it is very weak on the metathorax, weak on the 1st and 

 2nd abdominal segments, strongest on the central segments and con- 

 tinues well-marked on the 6th, 7th and 8th abdominals. It contains 

 three small slightly raised white spots (and two others are just 

 below it) on the 1st abdominal segment; several others on the 

 2nd abdominal segment on its upper edge and below. On the 

 1st subdivision of this segment a line of these spots runs up 

 towards the dorsal centre, sometimes nearly meeting those from 

 the other side of the larva, and further back there are a few 

 more white spots on the dorsal surface above the creamy line. 

 A somewhat similar arrangement exists on all the remaining 

 abdominal segments, but after the 3rd the number of white spots 

 diminishes, and on the 8th they are reduced to two or three or are 

 absent altogether. The creamy line has a dark green shading 

 below it especially towards the end of the body. The spiracles 

 are vertical black slits bordered narrowly with whitish. The true 

 legs pink outside and at the extremities, greenish inside. The 

 prolegs are pale brown but the fleshy parts of them are green. 

 The caudal horn pale yellowish, waxy looking; fairly straight, 

 inclined backwards, contracting abruptly about the centre, and 

 ending in a thin bayonet ; the surface granular, the bayonet so also 

 but more finely. The larva is slightly transparent, the contractions 

 and expansions of the dorsal vessel being clearly visible beneath 

 the dorsal surface on the 6th, 7th and 8th abdominal segments. 

 Fourth instar; Much like the last, the markings being of course 



