44 CATERPILLARS AND THEIR MOTHS 



grow older and the leaves begin to show their autumnal 

 coloring. Others have the surface color broken by 

 lines and patches of colors unlike the leaves and twigs 

 themselves, but resembling the effects of light and 

 shade on them as they grow, and such larvge blend 

 with their surroundings in a marvelous way. 



Some have eversible sacs which discharge an un- 

 pleasant fluid ; others have the power of protruding 

 horns or lashes which may or may not have a disa- 

 greeable odor. The lashes may be vibrated, as Cerura 

 vibrates those in its " fork-tails," and terrify some of 

 the foes that attack the caterpillar. It is thought 

 probable that the caudal horns of the sphingid larvae 

 formerly held terrifying lashes, and that these have 

 disappeared in the course of evolution, from dis- 

 use, the horn being left in most species. Others are 

 protected from devourers, but not from entomologists, 

 by an unpleasant taste. 



Early morning and near sunset are the best times 

 for finding caterpillars, as many kinds hide during the 

 day and feed at night or toward dark; still, we have 

 found hundreds in morning walks. The excrement, 

 or droppings, of the caterpillars often betrays their 

 hiding-place, and we have traced many by this means. 



Cocoons may be found in winter on bare branches, 

 bush-stems, tree-trunks, fences, among leaves on the 

 ground, or spun to all sorts of supports. These may 

 contain parasites. 



Pupae may be found in cellar-window areas, among 

 leaves on the ground, or by digging in potato- or 

 tomato-beds, or near trees or bushes where burrowing 

 larvae have fed ; but these are likely to be of stung 



