WHITES. 



157 



OP hedge garlic (Erysimum alliaria), dame's 

 cress (Hesperis matronalis), tower mustard 

 (Tumtia glabra), winter cress or yellow 

 rocket (Barbarea wdgaris), and occasionally 

 on lady's smock (Cardamine pratensis), as 

 stated by Mr. Doubleday, who observes, with 

 his usual care, that in this instance the 

 greater part of the caterpillars must perish 

 when the meadows are mowed, as the 

 plaut is cut down with the grass before tliey 

 are full-fed : it is very probable also that 

 other species of cruciferous plants are occa- 

 sionally selected in the absence of those 

 mentioned above, but I know of no othei-s 

 which have been noticed in England. When 

 the young CATERPILLAR emerges from the egg 

 it makes its way up the flowering-stalk, and 

 as soon as the pods have formed begins de- 

 vouring them : at first it requires but little 

 food, and the pods, growing with great 

 rapidity, fully keep pace with its require- 

 ments, and furnish an abundant supply. It is 

 curious to observe with what pertinacity these 

 caterpillars, in confinement, select the pods 

 and neglect the leaves of these plants, and, 

 having watched their proceedings with great 

 attention, I have fancied they devoured the 

 seeds with peculiar relish : sometimes a 

 pod will be pierced exactly over each seed, 

 and the seeds themselves consumed, the pod 

 being neglected until the supply of the more 

 favourite viand had failed. When full-fed, 

 which is during the first week in July, the 

 caterpillar rests in a nearly straight position 

 on the stalk or seed-pod of its food- plant: the 

 head is then of exactly the same breadth as 

 the second segment, and the body of nearly 

 equal breadth throughout, but slightly atten- 

 uated towards the anal extremity, which is 

 rounded ; the dorsal surface is convex, trans- 

 versely and regularly wrinkled, the wrinkles 

 dividing each segment into sections; the sides 

 are slightly dilated below the spiracles, and 

 the ventral surface slightly flattened ; every 

 part of the head and body is be^et with minute 

 warts, and each wart emits a short bristle. 

 The colour of the head and body is opaque 

 glaucous green, this colour on each side of 

 the body fading through pale glaucous green 



into white, the extreme margin of the lateral 

 dilatation being pure white, and constituting 

 a lateral stripe which has its upper or dorsal 

 margin very indistinctly defined, but its lower 

 or ventral margin abrupt and well marked ; 

 this white stripe encloses the very pale 

 spiracles, and extends the entire length of 

 the caterpillar, commencing at the ocelli close 

 to the mouth, and term i";i ting at the rounded 

 extremity of the anal flap ; the ventral sur- 

 face, legs and claspers, are dark-appte-green ; 

 the warts on the dorsal surface are intensely 

 black, and also many of those on the sides and 

 ventral surface, but in these regions there 

 occur white warts also, more especially within 

 the white lateral stripe ; the bristles which 

 they emit are black on the dorsal, and generally 

 black also on the ventral surface, but on the 

 lateral stripe they are mostly white. In July 

 the caterpillar ascends the stem of its food- 

 plant, and, fastening itself thereto by a belt 

 round the middle, changes to a crescent-shaped 

 CHRYSALIS of very eccentric appearance, both 

 extremities being elongated and pointed, and 

 the anterior elevated in the air, the posterior 

 firmly attached by a series of minute hooks to 

 a silken film, previously spun on the stalk of 

 the food-plant; the back is concave, the wing- 

 cases protruding and forming a semicircular 

 arch in the centre of the ventral surface; the 

 colour is pale dingy green, approaching to 

 wainscot-brown : in this state it remains 

 throughout the winter. Newman. 



TIME OF APPEARANCE. May. 



LOCALITIES. Meadows and lanes every- 

 where in the three kingdoms, as well as in 

 the Isle of Man. Mr. Birchall says it was 

 common in May, 1860, and that he observed 

 it in myriads at Sligo, reminding him of 

 the migrating clouds of tropical Callidryas ; 

 Mrs. Battersby says it is very common in 

 Ireland, and Mr. Fetherstonhaugh that it is 

 abundant in the counties of Dublin and 

 Mayo ; according to Dr. Buchanan White, it 

 is widely distributed in the lowland part of 

 country, and occasionally is rather common: 

 it has not been found north of Forres ; the 

 dates on which Dr. White has taken it in 

 Perthshire are as follows In 1858, May 15; 



