132 NORTH AMERICAN INSECTS. 



pass the winter as cocoons, exposed to rain, snow, and the 

 severest cold without the least injury. 



A few Butterflies, however, are not unfrequently seen on 

 warm sunny days in the middle of winter ; as, for instance, 

 the Thistle Butterfly (Vanessa carclui), or the Mourner's 

 Mantle {Vanessa AiitiojJe). These individuals came out 

 from their cocoons late in the fall, and made their winter- 

 quarters in hollow trees. 



As the habits and mode of life of Moths and Butterflies, 

 and even their forms and organs are quite uniform, while 

 on the contrary those of their caterpillars are very manifold 

 and diverse, the careful observation of the latter seems to 

 offer greater satisfaction to our curiosity, and I deem it im- 

 portant to speak more at length concerning them. 



Caterpillars have two kinds of feet, viz. : three pairs of 

 horny ones under the neck, and a number of fleshy ones un- 

 der the remaining parts of their body. The greatest part 

 of these insects have eight pairs of feet, some genera seven, 

 others six, and others only five, or even four pairs of feet. 

 Those that have eight pairs of feet v/alk very slowly and 

 uniformly on the ground, but all that have less than that 

 number walk differently ; they can not progress with their 

 body extended horizontally, but when creeping forward 

 form an arch with the middle part of the body, which is 

 destitute of legs, by approaching their hind feet to those of 

 the thorax, and then advancing with the forepart of the 

 body in the same manner as we move the hand when meas- 

 uring a span with the thumb and forefinger. On this ac- 

 count these caterpillars have been called by the common peo- 

 ple tailors, and by others geometrse, or surveyors. Those 

 caterpillars which have only four pairs of feet are able to 

 stand erect on their hind feet for hours, forming an acute or 

 a right angle, and in this motionless position resembling a 

 little twig of the shrub or tree upon which they are standing. 



Caterpillars are generally covered with very handsome 



