PROTECTIVE DEVICES 



59 



ifr^* 



FIG. 50. Mimicking and mimicked forms. Forms with W are wasps, with protective 

 stings. All the others are moths resembling wasps. Photographed by V. L. Kellogg. 



cause when the beak presses the insect's body, therefrom 

 is emitted a rank carroty odor extremely distasteful to 

 the bird. Possibly every young bird has this lesson to 

 learn at least once --that is, that this brown, black- 

 marked butterfly is not a dainty tidbit. And may we 

 not say that this lesson after repeated learnings by 

 successive generations becomes instinctive, and the in- 

 sect immune from the attack of the birds ? 



All this is of great importance in determining the 





