116 BRANCH ARTHROPODA 



insects and of other animals is indirectly due to two causes: 

 first, the advantages given to the individual or species in the 

 struggle for existence by these specific colors and color-patterns, 

 which — as in the case of the gray moth on the tree-trunk or 

 the katy-did among the green leaves — helps to conceal them 



Fig. SS. — Larva of regal walnut moth (Cithero'nia rega'Us) extended (two- 

 thirds nat. size). (Photographed from life.) 



from their enemies by affording protective resemblance, or — as 

 in the case of the bumble-bee or the milkweed butterfly — to 

 warn the enemy of the danger of sting or of the disagreeable odor 

 and taste. The advantage gained is easy to be seen in each 



Fig. S9. — Pupa of regal walnut moth (three-quarters nat. size). (From 



life.) 



case. They believe that these particular color-patterns are 

 due, in the second place, to gradual development " through 

 natural selection of naturally occurring, advantageous varia- 

 tions." 



The direct catise of color ma>- In^ chemical, depending on the 



