Observations on Insects affecting the Turnij) Crojjs. 307 



the under sides arc alike in both sexes, the upper wings being- 

 white, with the tips yellow, and two large black spots near the 

 centre; the under wings are likewise palish yellow, freckled with 

 black ; the head (fig. 2) is furnished with two hairy feelers in 

 front, called palpi, the tips being pointed (a), and between them 

 is concealed a long spiral tongue or proboscis (Z>). 



The female deposits her eggs on various cruciferous plants, 

 especially cabbages, turnips, mustard, rape, radishes, horse- 

 radish, and water-cresses : they are laid on the under side of the 

 leaves, in clusters of twenty or thirty (fig. 3), and are somewhat 

 of the shape of a sugar-loaf, bright yellow, and curiously furrowed 

 and reticulated, as shown in the magnified fig. 4. There is a 

 constant succession of broods during the summer and autumn ; 

 one which attracted my notice hatched the 27th of August, and 

 the little caterpillars immediately consumed all the egg-shells : on 

 the following day they were like fig. 5, green before and yellow 

 behind ; a little hairy, with the head, two spots on the first thoracic 

 segment, another on the tail, and numerous little dots, black : 

 they kept together, feeding upon the turnip-leaf in groups, and 

 in one night a single family ate a large hole completely through ; 

 they had 6 pectoral, 8 abdominal, and 2 anal feet, and possessed 

 the power of spinning a fine slight web over the surface, probably 

 to enable them to hold more securely to their food : in six days 

 they changed their skins, after which they dispersed over the 

 leaves ; in about the same space of time they cast their skins a 

 second time, when they were at least half an inch long, leaving 

 their exuviae sticking to the stalks (fig. 6). When full grown 

 they attain the length of about an inch and a half, and are as 

 thick as a small goose -quill ; they are then pale blue or green 

 above, yellow beneath, with a line of the same colour down the 

 back, edged with black dots ; there is likewise a row of large 

 black spots down each side, and numerous minute dots as well as 

 fine hairs scattered over the body (fig. 7) . Having arrived at this 

 stage, they generally wander to some secure place, under ledges 

 of paling, coping of walls, branches of trees, hedges, &c., and 

 there attach their tails to some object, by very tough silken 

 threads, and afterwards spin a similar cord from their mouths, 

 which is fastened round the animal to support its head in an ele- 

 vated position (fig. 8 c), and, gradually contracting its body, the 

 skin is slipped off, and it is instantly changed to a shining pale 

 green chrysalis, spotted and dotted with black (fig. 8), and in 

 this tranquil state the latter broods rest suspended, uninjured by 

 the storms and frosts of winter, until the genial warmth of spring 

 calls the sleeping inmate into active life, and, as this proceeds, the 

 black spots of the wings, although in miniature, gradually become 

 more distinct through the horny transparent shell, and eventually 



