vii DEFENCES OF INSECTS 253 



which is highly nauseous. If the structure is seized 

 by the enemy, and apparently it is a most convenient 

 point to capture, it breaks off without harm to the 

 owner, but with such uncomfortable effects on the 

 attacking animal that the former probably escapes 

 unhurt. 



In other cases, a non-vital part is particularly 

 attractive but is unattended by unpleasant qualities. 

 The part gives way upon seizure, so that the insect 

 is afforded a chance of escape. This is probably a 

 meaning of the broad expanse of wing of many 

 weak-flying butterflies, and of their bright colouration 

 irrespective of its pronounced sexual utility. Such 

 butterflies are tolerably plentiful, poor as one might 

 deem their opportunities for existence and increase. 

 But specimens are often taken with pierced and 

 broken wings, as though they had been caught 

 and had escaped. Wings that were less showy in 

 flight would not have constituted so good a target, 

 and had they been smaller in proportion to the body 

 the enemy would have been more likely to hit upon 

 a vital spot. Where the butterfly is active, and has 

 well developed protective tints, its brilliant colour 

 leaving the greater sexual use out of the question 

 serves as protection in reserve after its other 

 defences have broken through, and attracts enemies 

 to some feature of no importance, when it has failed 

 to elude its pursuer either by its swiftness or by its 

 disguise. This colour differs from Warning Colour 

 proper. It is associated with protective tints, and 

 the enemy, although it makes a mistake, is un- 

 affected by disgust or danger. 



