Warning Colour — Mimicry 321 



be enemies. A single peck from a bird's beak, trying 

 the edibility of a caterpillar, would prove fatal to the 

 latter whether it were subsequently eaten or not ; it 

 is therefore decidedly to the insect's advantage to be 

 quickly recognised as unpalatable and to be left 

 untouched (184), 



Among insects adorned with these warning colours 

 wasps and bees are undoubtedly dangerous on account 

 of their stings. The beetles, moths, butterflies, and 

 caterpillars, are believed to be provided with noxious 

 secretions which make them unpalatable to birds, 

 lizards, and other insect-eating animals. Many experi- 

 ments have been made with the object of testing the 

 edibility of these insects, and it has often been found 

 that birds which greedily devour insects with protective 

 coloration as soon as they can detect them, refuse to 

 touch those displaying warning colours. But evidence 

 has been produced to show that this distaste for 

 brightly-coloured insects is not universal; occasionally 

 at least they are devoured despite their nature and 

 appearance. On this account some naturalists have 

 doubted whether warning colours really have the 

 meaning usually ascribed to them (185). But no kind 

 of protection can avail at all times and in all cases. 

 The struggle for life among insect-eating animals 

 must lead some to acquire the power of feeding on 

 kinds which others cannot touch. And the fact that 

 brilliantly-hued insects at times fall victims to hungry 

 birds, lizards, or monkeys, cannot destroy the experi- 

 mental evidence that bright colours are commonly 

 associated with hurtful or nasty qualities. 



Mimicry. — Strong testimony to the value of warn- 

 ing colours is afforded by the likeness which harmless 

 insects sometimes bear to dangerous or noxious kinds. 

 Clearwing moths (Sesiidx) with their black and yellow 

 banded bodies and wings almost destitute of scaly cover- 



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