THE COLORATION OF ANIMALS 



69 



a caterpillar of the common elephant hawk-moth (Gkcerocampa 

 elpenor) in the feeding-trough of a hencoop, and a sparrow Hew down 

 to feed from the trough. It descended at first with its back to 

 the caterpillar and fed cheerily. But when by chance it turned round, 

 and spied the caterpillar, it scurried hastily away. 



Among Lepidoptera, too, eye-spots often occur on the wings, and 

 to some extent, at least, they have in this case also the significance 

 of warning marks. Take, for instance, the large blue and black 

 eye-spots on the posterior wings of the eyed hawk-moth (Smerin- 

 thus ocellatus). When the insect is sitting quietly the two spots are 

 not visible, as they are covered by the anterior wings, but as soon as the 

 creature is alarmed it spreads all four wings, and now both eyes stand 



Fig. 5. The Eyed Hawk-moth in its 'terrifying attitude.' 



boldly out on the red posterior wings and alarm the assailant, as they 

 give the impression of the head of a much larger animal (see Fig. ~ } ). 

 There are also eye-like spots which have not this significance and 

 effect, as, for instance, the ' eye-spots ' on the train-feathers of the 

 peacock and the Argus pheasant, or the little eye-like spots on the 

 under surface of many diurnal butterflies. In the first case, it is 

 a matter of decoration ; in the second, perhaps of the mimicry of dew- 

 drops, which increases still further the resemblance to a withered 

 leaf; but there are undoubtedly many cases in which the eye-spots 

 serve as means of frightening off enemies, and these cases are especially 

 common among butterflies. 



Such warning marks are in no way contradictory to the 

 sympathetic colouring of the rest of the body, and indeed we usually 

 find them in combination with it. In some cases the eye-spot, though 

 very conspicuous, is covered, as in the eyed hawk-moth, when at rest, 



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