20 NATURE SKETCHES IN TEMPERATE AMERICA 



their strange disguises. The simulation of animals to other 

 objects has been designated as "protective resemblance and 

 mimicry." A great amount of attention was bestowed on this 

 subject by Wallace in supporting the theory of natural selection. 



Almost every one is familiar with some type of animal which 

 resembles in a remarkable degree either the ground, or the bark 

 of trees, or the vegetation upon which it lives. I will draw 

 attention here to only two examples, namely: the arboreal 

 katydid and cone-head grasshoppers, the legends under each 

 figure explaining them. In the following pages are shown the 

 walking-stick, common grasshoppers, stick larva, moths resem- 

 bling leaves, as well as other examples serving as illustrations. 



Examples of protective resemblance differ from examples 

 of mimicry in that the former have the body colors assimilate 

 with their environment, while in mimicry the animal bears a 

 resemblance to a living animal usually possessing some special 

 means of protection and supposed thereby to enjoy a certain 

 immunity from attack by predaceous animals. The animal 

 mimicked has some special structure which makes it distasteful 

 to its enemies which prey upon it. Common examples of 

 mimicry are found in butterflies, where one species possesses 

 a scent which is said to be nauseous to birds, and the 

 color pattern of that species is mimicked by other species of 

 butterfly belonging to another genus. Then, there is the robber 

 fly (described further on), which masquerades as a bumblebee, 

 and in this mimicry is not only presumed to be protected, 

 but is able to steal upon its prey unsuspected. In this means 

 of protection natural selection is supposed to have been a 

 factor in preserving modifications of structure. It is through 

 slight differentiations and modifications; of structure with 

 transmission by inheritance that these extreme specializations 

 of form appear to have been brought about. 



Coexistent with these changes in animal life are modifications 

 in the structure of plant life. For example, in some of the 

 higher plants we find a great variety of the blossoms so modified 

 and dependent upon the insect life that it is supposed that 

 they would become exterminated were the insects that effect 

 pollination to die out. 



The period in which plants blossom is presumed to be brought 



