THE LAKE OF PITCH. 41 



which gives them the name of the owl butterfly. But however 

 much, in an insect cabinet, the expanded reverse of the wings 

 suggests the face of an owl, the spot, as we observed it in the 

 forest, seemed rather to render the insect invisible. These 

 great fellows would shoot up to a lichen-covered trunk and 

 drop lightly upon it, and unless one's eyes had followed 





FIG. 20. YELLOW WOODPECKER. 



closely, the butterfly vanished like magic. Creeping up to 

 one we secured its picture, the mottlings on its wings merg- 

 ing it with the lichens, and its owl-eyes becoming the painted 

 facsimiles of darkened knotholes, or of little atoll-like fungus 

 rings. 



One is constantly impressed by the abundance and variety 

 of these protective adaptations. Instead of one's eyes be- 



