165 
But when these disappear, other insect-eaters come upon 
the scene. 
“ The tree-creepers and the tits, insectivorous in their propensities, 
are content to seek food in the crevices of bark up and down the 
branches of old trees, in the cracks of walls, in and out among the 
stones and bricks of old buildings, peering, probing, pecking at 
the creatures that have thought to get safely through the cold weather 
by hiding.”—{Ibid. p. 164.) 
Our winter migrants find in our 
“ . . . river estuaries, oozy mudbanks and golden sands, among 
other things larvae and all manner of marine insects. . . . Inland 
too, we have stores of bird-food in winter. Very seldom indeed is 
the ground so hard frozen that the rooks and the thrushes cannot 
probe it with their long bills and find here a worm and there a grub, 
and there the larva of some bright butterfly.”—{Ibid. p. 163.) 
Even in the season when insects fully developed are on 
the wing, they are not saved merely by the colours which 
they assume. 
“ It seems probable, that in some cases, that which would appear 
at first to be a source of danger to its possessor may really be a 
means of protection. Many showy and weak-flying butterflies have 
a very broad expanse of wing. . . . They are often captured with 
pierced and broken wings as if they had been seized by birds from 
which they had escaped. But if the wings had been smaller in 
proportion to the body, it seems probable that the insect would 
be more frequently struck or pierced in a vital part.”—(Wallace. 
Contributions, p. 33.) 
Thus the increased expanse of wing has been a source 
of safety which has hindered the action of Natural Selec 
tion in its attempt to weed out some of the variants. 
So far as the modification of colour is concerned, it may 
further be observed that the coloration of the wings assists 
in enhancing this immunity from destruction. 
“The brilliant colour is so placed as to serve for protection ; as, for 
example, the eye-spots on the hind wings of moths which are pierced 
by birds, and so save the vital parts of the insect ; while the bright