THE SWALLOW-TAIL AND THE 'WHITES' 145 



as ' Whites,' a glance at a few specimens will show that they are 

 not really white at all, but exhibit delicate shades of cream and 

 yellow, inclining sometimes to buff. The under surfaces are par- 

 ticularly noticeable in this respect, for here the hind wings and the 

 tips of the fore wings display a very rich yellow. 



The species we are now considering is also very variable both in 

 its ground colour and the markings of the wings. The former is in 

 some cases a really brilliant yellow ; and the latter are in some 

 cases entirely wanting. 



Bapce is double-brooded, the first brood appearing in April and 

 May, and the other in July and August. 



During these months the eggs may be seen in plenty on its 

 numerous food plants, which include the cabbages and horse-radish 

 of our gardens, also water-cress (Nasturtuim officinale), rape 

 {Brassica Na2)i(s), wild nmstard {B. Sina2>is), wild mignonette 

 {Bescda lutca), and nasturtium {Tropcrolnxi majiia). 



The eggs are conical in form — something like a sugar loaf, witli 

 ridges running from apex to base, and very delicate hues from 

 ridge to ridge transversely. 



The young larviP often make their first meal of the shell, and 

 then attack the food plant so voraciously that they are fully grown 

 in about three or four weeks. In colour they are of a beautiful 

 glaucous green, hardly distinguishable at times from the leaves on 

 which they rest. A jellow stripe runs along the middle of the 

 back, and lines of yellow spots adorn the sides ; and the whole body 

 is covered with very short hairs, each one arising from a minute 

 warty projection. 



The pupse may be found during the same seasons and in the 

 same situations as those of Brassicce. Thej' are very variable in 

 colour. Some are of a very pale grey or putty colour, some are 

 decidedly brown, and others of a greenish tinge ; and they are 

 often spotted and striped with dark grey or black. 



Tlie Grccn-veincd White (P. Napi) 



A non-observant beginner at entomological work may easily 

 mistake this insect for the last species, for the ground colour and 

 markings are very similar, even to the features by which the sexes 

 are distingviished from each other ; but an inspection of the under 

 surface will give s. readj' means of identification, for here the wing 

 rays are border-ed A\-ith black scales which, by contrast with the 



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