Pl. 15.
Orange-tip Butterfly.
Egg, natural size and enlarged; caterpillar and chrysalis.
The caterpillars feed in June and July on lady's smock or cuckoo-flower (Cardamine pratensis), charlock (Brassica sinapistrum), hedge-mustard (Sisymbrium officinale), garlic mustard (S. alliaria), rock-cress (Arabis), horseradish (Cochlearia armoracia), dame's violet (Hesperis matronalis), watercress (Nasturtium officinale), etc.
The chrysalis, as will be seen from the figure (Plate [15]), is curiously elongated, and tapers towards each end; the outline of the back is curved, and the wing-cases bulge out into an angle about the middle of the under side. The colour is pale grey or whitey-brown, sometimes with a strong rosy tinge; the back is speckled with brownish, and has an olive-grey dorsal line, and the veins of the wings are well defined. This stage lasts, as a rule, from August of one year until May of the following year. When the chrysalis is first formed, it is green, with the wing-cases brighter, and this colour is sometimes retained. It has been stated that the chrysalids assume the colour of their immediate surroundings, and this may be so; but all that I have had under observation were of the colours described above, although some were fastened to green stem, others to muslin, and others, again, to glass.
Towards the end of May and in June is the usual time for this butterfly to be on the wing. It has, however, been noticed as early as about the middle of April, and as late as the middle of July, and rarely in August and September. The specimens, seen in the last-mentioned months, may have represented a second brood, and, if so, a very unusual event. Possibly, however, they may have been specimens whose emergence had for some reason not understood, been retarded. There is at least one record of the insect remaining in the chrysalis for two winters.
Although generally distributed throughout England, Wales, and Ireland, and occurring in Scotland as far north as the Caledonian Canal, it seems to be more common in some districts than in others. Abroad, its range extends over Europe, and through Asia as far east as Amurland and China.