176 THE COLOURS OF ANIMALS 



in other ways. But the larva must feed, and at the 

 same time is sluggish in its movements, defenceless, 

 and when palatable is more reHshed than any other 

 stage, for it does not possess the hard investment of 

 the one or the scaly covering of the other. Hence it 

 is that the great needs of the larva have been so fre- 

 quently met in this way; but as soon as the un- 

 pleasant quality has appeared it will tend to pass on 

 by simple continuity into the other stages. If these 

 latter are hard pressed, there is always the possibility 

 that such qualities may be made the starting-point of 

 a similar method of defence for them also. But the 

 disagreeable properties may also pass on into stages 

 which hold their own successfully by elaborate and 

 perfect Protective Eesemblances, and then such quali- 

 ties, unattended by Warning Colours, are entirely use- 

 less to the stage, but may be important as a latent 

 possibility for the future. It must be remembered 

 that an unpleasant attribute must always appear in 

 advance of the warning colomdng. An example is 

 afforded by the Buff-tip Moth {Pygcera hucephala)^ 

 which is beautifully protected, during rest, by resem- 

 bling a piece of rotten lichen-covered stick (see page 

 57), but which nevertheless retains something of the 

 unpleasant taste by which its caterpillar is effectually 

 protected. 



