INTRODUCTION 25 



on or near the ground, the upper part of the body exposed 

 to the direct light from above is dark; and the under part, 

 shut off from the upper Hght and receiving only the small 

 reflection from below, is enough lighter to make the ap- 

 pearance of the creature in its natural environment of a 

 uniform tone from back to breast. 



Nearly all caterpillars illustrate this law of counter- 

 shading. If they are in the habit of feeding or resting with 

 their feet downward the back will be darker and the un- 

 der side lighter, but if they are in the habit of feeding or 

 resting in the opposite position these color tones will be 

 reversed. One can find examples of such conditions al- 

 most any summer's day by a httle searching of trees or 

 shrubs. 



This law of counter-shading, however, is really only the 

 basis for the coloration of caterpillars or other animals. It 

 tends, chiefly, to make the creature appear as a flat plane 

 when seen from the side, and may be said in a way to pre- 

 pare the canvas upon which Nature paints her more dis- 

 tinctive pictures. A great many examples of color mark- 

 ings that tend to conceal the caterpillar amid its natural 

 surroundings may be found by any one who will study the 

 subject and it offers one of the most interesting fields for 

 investigation. The chapter on caterpillars in the above- 

 mentioned book by Mr. Thayer should serve as a starting 

 point for any one taking up the subject. 



Butterflies differ from caterpillars and from most other 

 animals in the fact that their coloring is chiefly shown upon 

 the flat surfaces of the wings. Consequently, there is less 

 opportunity for the various phases of counter-shading 

 which is so commonly shown in the larger caterpillars. 

 The bodies of nearly all butterflies do exhibit this phenom- 



