Color and Pattern and their Uses 599 



Now that we have got in some degree acquainted with the ways in which 

 colors are actually produced among insects, we may come back to the ques- 

 tion asked in the first paragraph of this chapter, namely, "What is the use 

 to the insect of all this variety of color and pattern?" We may attempt now 

 to get some clue to the significance of the color phenomenon. So wide-spread 

 and well developed are color and pattern among insects that the presump- 

 tion is strong that the utility of color-pattern is large. 



The only hypothesis that gives to colors and markings a value in the life 

 of insects at all comparable with the degree of specialization reached by 

 these colors and markings and by the special structures developed to make 

 them possible, is that already referred to as the theory of protective and 

 aggressive resemblances, of warning and directive patterns, and of mimicry. 

 These various uses of color-patterns are all concerned with the relation of 

 the insect to its environment; they are means of protecting the insect from 

 its enemies or of enabling it to capture its prey. They are uses obviously con- 

 cerned with the "struggle for existence"; they are "shifts for a living." 

 For the sake of clearness in the discussion of these various uses— a discussion 

 which must by the limitations of space be most unsatisfactorily condensed — 

 the uses will be rather arbitrarily classified into several categories which in 

 Nature are not as sharply distinguished as the paragraph treatment of them 

 might suggest. 



General protective resemblance. — The general harmonizing in color and 

 pattern with the color scheme of the usual environment is a condition which 

 every field student of insects recognizes as widely existing. The difBculty 

 of distinguishing a resting moth from the bark on which it is resting, a green 

 caterpillar or leaf-hopper or meadow grasshopper from the leaf to which it 

 clings, a roadside locust or bug from the soil on which it alights, is a diffi- 

 cultv which has to be reckoned with by every collector. Now while there 

 are few human collectors of in.sects, there are hosts of bird and toad and lizard 

 insect-hunters, to say nothing of the many kinds of predaceous insects them- 

 selves who use their own cousins for chief food. So that where this diffi- 

 culty of distinguishing the resting insect from its environment is sufficient 

 to postpone success on the part of the insect-hunting bird or lizard, the life 

 of the protectively-colored insect is obviously saved, for the time, by its dress. 

 This is a utility of color and pattern than which there can be, from the insect 

 point of view, nothing higher. 



Variable protective resemblance. — While with most insects all the indi- 

 viduals of one species show a similar color and pattern, it is noticeable that 

 with a few species there is a marked variabil'ty or difference in color and 

 sometimes in markings. Locusts of various species of the genus Trimcro- 

 tropis show a variability in color of individuals ranging through gray, brown, 

 reddish, plumbeous, and bluish, and such accompanying variab lily in mark- 



