220 COI.ORATION IN IvEPTINOTARSA. 



Utility by one hypothesis is one thing, and very easy, but to determine the 

 cause of the phenomena is quite another, and not easy. 



The most approved current hypothesis employed in the explanation of the 

 phenomenon of warning coloration is that of natural selection. All are 

 familiar with the use made of this hypothesis by Darwin, Wallace, and later 

 writers in their treatment of the subject of protective coloration, and the 

 plausible explanations that have been made upon the basis of this hypothesis 

 of natural selection. While I think that no one can doubt the utility of the 

 end result — that is, the fully developed warning coloration — it is indisputable 

 that we are as yet ignorant of the earlier stages in the development of warn- 

 ing coloration, excepting as we create them in our imagination. No one, to 

 my knowledge, has as yet recorded from actual observation the beginning of 

 the development of warning coloration either in nature or in experiment, and 

 the supposed utility of the initial stages still remain an unproven assumption. 

 Altogether the explanation of warning coloration by natural selection, while 

 it may be a true one, is at present based upon assum.ptions the correctness of 

 which is open to doubt. Those writers who, in highly involved language and 

 through circuitous logic, dogmatically assert that these phenomena "can only" 

 have come about by natural selection, are themselves indulging in the same 

 dogmatism as that which once so generally characterized a kindred branch of 

 human knowledge, and which the same scientists have vigorously denounced 

 and held up to ridicule. In Leptinotarsa we shall for the present recognize 

 the existence and utility of the phenomenon of warning coloration without 

 attempting at present to account for its production. 



PROT^CTIV^ RI:SEMBI,ANCE:. 



The widespread distribution of this phenomenon among all animals, and 

 especially among insects, and the interest which these wonderful adaptations 

 have aroused, have made them the basis of some of the wildest and most 

 absurd speculations to be found in modern biological literature. 



In Leptinotarsa color adaptations which arise as protective resemblances 

 are not numerous. The eggs, many of the larvae, and most adults are con- 

 spicuously colored. Some few larvae, however, do show protective coloration 

 in the early stages. Thus, in multitceniata, oblongata, rnhicunda, and melano- 

 thorax the young larvae are all light yellow, exactly the color of the long yel- 

 low spines on their food plants, among which they rest. In these larvae the 

 only protection comes from the general correspondence in color, and is, I 

 believe, purely a matter of accident, and not an adaptation. At any rate, the 

 larvae quite as frequently lie on the green part of the plant as upon the yellow 

 spines, and it would take more imagination than I possess to make out of this 

 a case of protective resemblance. 



Some larvae, undecimlineata, diversa, signaticollis, dilecta, violescens, liba- 

 trix, and other species, are colorless, or nearly so, in certain stages. This 



