100 NATURE SKETCHES IN TEMPERATE AMERICA 



and are in consequence so well protected that this extensive 

 genus comprises about a hundred species in our North 

 American fauna. 



The drawing of the moth shown in my initial illustration is 

 that of the nearly allied Homoptera cinguUJera, one of the night- 

 flying moths. Its underwings are streaked grayish brown, some- 

 what like the front pair. Its larva is almost indistinguishable 

 from the one I have shown at the top of the preceding page. 



Poulton, in his "Color in Animals," gives some interesting 

 experiments on similar larvae which resemble twigs or the bark 

 of their food plant. They were carried out to determine what 

 influence, if any, the environment might have in determining 

 the color. The caterpillars were surrounded by the leaves 

 upon which they fed, and also In' white or green surfaces. 

 No brown twig, or anything dark colored, was allowed to come 

 near them during their whole life. Under these circumstances 

 the larvae in the majority of the species selected for experiment 

 became very light brown or light gray in color and tpiitc unlike 

 the darker larvae of the same kinds which were produced when 

 an al)undance of dark twigs had been mixed with the leaves 

 of the food j)l;uit. Thus it was shown that the environment 

 had some influence on the colors of these larva\' 



•Sec also Morpan, "Experimental Zoology," 1907, p. 12, on the influence 

 of external conditions. 



