324 



TEXT-BOOK OF ZOOLOGY 



insect's safety, though it renders it more conspicuous than other allied 

 but darker-coloured species ; every flying animal, however, by its motion 

 alone attracts the notice of its enemies, even though its colours are quite 

 inconspicuous. The capacity for flight, and more especially the reeling, 

 unsteady, inconstant and incalculable character of this flight, are to the 

 cabbage butterfly (as to all other diurnal butterflies) a very important 

 means of protection against its enemies. (Enter into this more 

 fully.) 



But does not its conspicuous garment betray its'presence when it has 

 settled down to rest ? might one not expect it really to invite the atten- 

 tion of enemies ? That such is nowise the case everyone knows who 



has found the insect asleep among 

 leaves, and half frozen with the night 

 cold. In this condition the insect folds 

 its wings together in such a manner 

 that they come to stand vertically erect. 

 Moreover, since the hind-wings cover 

 the front-wings in such a manner as to 

 leave only the tips of the latter visible, 

 the wings now do not appear half as 

 large as when expanded. Further, on 

 examining the colour of the under side, 

 we shall note the following interesting 

 fact : All that part of the fore- wings 

 which is covered by the hind-wings is 

 (with the exception of the two black 

 spots — see above) pure white ; that 

 portion, on the oilier hand, which is not 

 so covered is, like the hind-wings, of a 

 dirty greenish-yeUow colour, so that 

 amid the tangled foliage the insect 

 looks like the leaves, and is easily 

 lost to view. 



Of course, none of these means of 

 protection are perfect (such, in fact, do not occur in Nature). But by its 

 great fertility (see Section A) the insect speedily fills up the gaps made 

 by foes amidst its ranks. (This also explains why so-called "rare" 

 butterflies, i.e., those whose larvae are limited to a single food plant, or to 

 a few scarce plants, require a more effective protective coloration, since 

 otherwise they would long since have become extinct; see following 

 section.) 



2. Several other peculiarities of structure are intimately connected 



Head of the White Cabbage Butter- 

 fly (magnified), and on the Left 

 a Portion of the Proboscis (more 

 highly magnified). 



F., Antennee ; A. , eye ; R. , proboscis ; 

 Lt., labial palpi. 



