ADAPTATION IN COLORATION. 221 



semi-transparent condition is usually found in the second instar, when the 

 larva is full of clear hzemolymph and the fat body has not yet developed. 

 They are then translucent, and resemble closely the color of their food plant. 

 This combination of conditions, which gives a considerable degree of conceal- 

 ment to the larvae, is to be interpreted as accidental, and not as a real adapta- 

 tion for the purpose of concealment and protection. 



The adults of Leptinotarsa, as far as I know, present no protective resem- 

 blances in color adaptation, but all show the warning coloration already 

 described. Mimicry also is entirely wanting, and while it would be easy 

 to match up Leptinotarsa with species in Doryphora,Labidomera,Calligrapha, 

 Stilodcs, etc., and create cases of mimicry, there would be no foundation 

 in fact for them. If I had never seen these genera in nature, and did not 

 know that they and the species having similar color patterns are not found 

 together that is, if I knew them from museum specimens alone I might be 

 pardoned for creating with them more new cases of mimicry; but in these 

 beetles in nature there is not the slightest trace of mimetic phenomena, and 

 the creation of any cases of mimicry is, I believe, absolutely unpardonable 

 unless the cases have been thoroughly studied in nature. The literature is 

 already overloaded with purely imaginary examples of this phase of protective 

 coloration. 



The adaptations in coloration in Leptinotarsa are largely warning colora- 

 tion with a few examples of protective resemblance, and no really good evi- 

 dence has been found which would tend to show how these came into exist- 

 ence. It is true that oblongata, rnbicunda, and melanothorax all have warn- 

 ing colors, and that they arise by sudden transformation from multitceniata; 

 but multitceniata is itself provided with warning colors, and as these species 

 arise from a species in which warning colors were already developed, we shall 

 have to go farther back in their genealogy for the origin of the phenomenon. 

 These species afford evidence only of the transmissibility of warning colors 

 from species to species, and not of its first production. The fact that warning 

 coloration is handed on in evolution from species to species is, I believe, of 

 considerable importance. In these three species, at least, this character is 

 handed down from the parent species to the descendant species in its full 

 intensity. 



Inasmuch as this phenomenon is general throughout the genus, and is, as I 

 have just shown, handed on in evolution from one species to another, I con- 

 clude that the wide distribution of striking colors which serve as warning 

 colors has not been developed within the genus Leptinotarsa at all, but that it 

 is inherited by this genus from its ancestors. Hence it is not to be expected 

 that evidence of the origin of the phenomenon would be found in Leptino- 

 tarsa; and in my experiments with these beetles none has appeared. 



