6oo Color and Pattern and their Uses 



ing as to result in producing much variety of appearance in a single 

 series of collected individuals. I have noted in collecting these locusts in 

 Colorado and California that this variability of coloration is directly associ- 

 ated with the color-differences in the soil of the localities in which these locusts 

 live; the reddish individuals are taken from spots where the soil is reddish, 

 the grayish where it is sand-colored, and the plumbeous and bluish from soil 

 formed by decomposing bluish rock. 



On the campus of Stanford University there is a little pond whose shores 

 are covered in some places with bits of bluish rock, in other places with bits 

 of reddish rock, and in still others with sand. The toad-bug, Galgulus ocula- 

 tus, lives abundantly on the banks of this little lake. Specimens collected 

 from the blue rocks are bluish in ground-color, those from the red rocks 

 are reddish, and those from the sand are sand-colored. But the colors 

 of these insects are fixed; they cannot, like the chameleon and certain other 

 lizards, or like numerous small fishes and some tree-frogs, change color, 

 quickly or slowly, with changes in position, that is, movements from green 

 to brown or to other colored environment. Variable protective resemblance 

 in insects is, as far as known, a variability directly induced, to be sure, by 

 varying environment, but all acquired during the development of the in- 

 dividual insects, and fixed by the time they reach the adult stage. 



The well-known experiments of Trmen, Miiller, and Poulton with the 

 pupating larvae of swallow-tailed butterflies, Papilio sp., and Poulton on 

 other butterflies with naked chrysalids, show that the chrysalids of numerous 

 butterfly kinds take on the color, or a shade approaching it, of the substance 

 surrounding the pupating larvae, and show also that the result is due to a 

 stimulus of the skin by the enclosing color, and not to a stimulus received 

 through the eyes, and carried to the skin by the nerves. Larvae just ready 

 to pupate were enclosed in boxes lined with paper of different colors; the 

 chrysalids when formed were found to be colored to harmonize with that 

 particular color of paper by which they were surrounded while pupating. As 

 these chrysalids in Nature hang exposed on bark and in other unsheltered 

 places, without protecting cocoon or cover of any kind, the actual protective 

 value of this harmonious coloration is obvious. 



The larvae (caterpillars) of various moths, particularly Geometrid and 

 Sphingid species, often appear in two color types, one brown and the other 

 green. Poulton has shown by experiment and observation with some of 

 these species that those larvae reared among green leaves and twigs and 

 branches become brown. This variable protective resemblance, like that 

 of Trimerotropis, Galgulus, and the Papilio chrysalids, also is fixed after 

 being once acquired. 



An interesting example of color harmony whxh may be class fied under 

 the head of variable protective resemblance that has come under my obser- 



