22 



NATURAL HISTORY OF INSECTS. 



and twelfth segments; those under the twelfth segment are 



sometimes called the anal prolegs. Larvae having more 



than sixteen legs are Fi S- 16 - 



called/aZs0 Caterpillars, 



such as the larvae (Fig. 



60) of the Imported 



Currant Saw-fly, which 



is provided with twenty 



legs. The prolegs of 



these false caterpillars 



are not furnished with 



hooks at the tips. 



The false caterpillars 

 (Fig. 60), and also the 

 true caterpillars, which 

 are provided with six- 

 teen legs (Fig. 2), in 

 crawling about, move with a gently undulating motion, while 

 those which are provided with from ten to fourteen legs, arch 

 the body more or less upward. This is most noticeable in the 

 ten-legged caterpillars (Fig. 58), which are commonly called 

 "Span-worms," "Measuring-worms," or "Geometers." In 

 crawling about they arch the body upwards (Fig. 61), by 

 bringing their hind legs close to the front legs, then fastening 

 themselves by the intermediate and hind legs, they stretch out 



Fig. 61. 



Fig. 63. 



the body to its full length (Figs, 62 and 213); the same move- 

 ments are repeated in making the following steps. 



The caterpillars that are provided with twelve or fourteen 

 legs, in moving arch the body upward in the same manner as 

 those having ten legs, but to a less extent. 



