NATURE'S CALENDAR 131 



mies by spines, or hairs, or the abihty to \viti^ ii 



throw out some offensive liquid or odor, 



or they are of such a color as easily to be 

 overlooked. Thus caterpillars that draw 

 together the edges of a leaf, forming a 

 little house in which to conceal them- 

 selves, or that burrow in old wood or the 

 pith of living plants, are usually nearly 

 white, but those that travel about in view 

 are so colored as closely to resemble the 

 objects upon which they are accustomed 

 to stay and feed. Most of them, there- 

 fore, are of the. precise green of the leaves 

 whose juices they suck; others are gray 

 or brown, mimicking the bark and twigs 

 upon which they crawl. Many, it is true, 

 are of bright hues — yellow, red, or red- 

 brown, black and white, or striped, barred 

 and spotted with strong colors, foretell- 

 ing the brilliant ornamentation of the 

 winged adults to follow. Such are almost 



always guarded by their ugly knobbed or 

 horned appearance, or by an armature of 

 barbed prickles, or a covering of stiff 

 hairs, or by special organs of defence. 

 The caterpillars of the swallowtailed but- 

 terflies, for instance, are provided with a 

 sort of double-barrelled gun which may 

 be pushed out f'-om behind the head, and 

 it will discharge an odor disgusting to 

 insect-eating creatures. Most caterpillars 

 "resist arrest" by hurling their heads 

 from side to side, or by causing their 

 barbed and acrid spines or hairs to prick 

 and annoy their enemies ; these are usu- 



