22 LEPIDOPTERA. 



having a green suffusion from the nervures, have been shown 

 to be discoloured by accidental or artificial means, from rup- 

 ture of the nervures. 



In the Canaries an extraordinary variety is found, in 

 which the spots beneath are united into a large coarse black 

 " smudge." It is called var. chciraiitJii, and is totally un- 

 known here. 



Larva yellowish-green, with black spots, dorsal and 

 spiracular lines yellow. Head slate-coloured, dotted with 

 black, greenish-yellow beneath. Entirely covered with deli- 

 cate wliitisli hairs. 



Feeding on all the cultivated varieties of the cabbage, in 

 companies, passing the day side by side underneath the 

 leaves. Also on other Crucif<ra-, on Tropanlum majiis and 

 2xrcyrinutn, and even on Reseda. June and beginning of 

 July, and again in September and October, or even into 

 November. 



This second brood of larva- is, in favourable seasons, so 

 numerous that the whole crops of winter varieties of cabbage 

 are defoliated by it, to the gardener's intense disgust. In 

 these cases, however, it nearly always happens that a minute 

 parasite, Apcmtclcs glonieratus, has multiplied in even 

 greater proportion, and the vast majority of larvae, after 

 spinning up, produce a bunch of yellow cocoons instead of 

 the pupa. ■ Then the species is again reduced to moderate 

 numbers. 



The angulated greenish pupa, with black and yellow 

 dots, attached by its tail and a girth to walls, palings, and 

 tree trunks, is familiar to every one. It may be seen all 

 through the winter. 



The vast and sudden increase in numbers of the larva in the 

 autumn is evidently due at times to a great immigration of 

 the butterflies from abroad. Many cases are on record of the 

 appearance of vast flights of this species at sea, sometimes so 

 as to form clouds like a snow-storm, or to cover a vessel and 

 its sails when they alighted. Such flights have also been 



