100 ANIMAL COLOKATION. 



plants occarring among grasses. This very fact does not look 

 like selection; it looks much more like a family characteristic. 

 Still there is the coincidence of colour and habit. It has been 

 mentioned that the very young caterpillars are not striped; but 

 among tufts of bright green and luxuriantly-growing grass is 

 there any need for even the adult caterpillars to be striped ? 

 One does not notice the striping produced by the venation of 

 the grass leaves in many cases. As a matter of fact, some of 

 the Satyrid larvce are greener than others, and the striping is 

 reduced to the minimum of visibility. These species are 

 equally well, if not better, provided for in the way of protective 

 coloration than the brown ones with strongly marked linef. 



These Larvae usually feed by night, and often conceal themselves 



by day. 



The larviB of these butterflies feed chiefly by night ; under 

 these circumstances striping or no striping would be quite 

 immaterial, — they would run an equal risk of discovery with the 

 most brilliantly coloured of caterpillars. But although these 

 caterpillars usually, if not always, feed by night, they often 

 rest during the day freely exposed upon grass stems, so that 

 their protective coloration would stand them in good stead. 

 Immobility, as has already been remarked, is an absolutely 

 necessary concomitant of protective coloration. If the matter 

 ended here, there would be considerable grounds — almost 

 perfectly convincing indeed— for regarding the coloration of the 

 caterpillars as due to adaptation. But this is not all. 



Several species hide themselves by day ; Newman * relates 



that this is the case with the "Grayling" butterfly, Hipparckia 



semele. A number of these larviK were observed not only to 



feed during the night, but to hide themselves during the day 



* " British Butterflies and Moths." 



