124 



INSECT TRANSFORMATION 



abdominal segment. This is a typical arrangement among the 

 Lepidoptera, the number of five pairs being very rarely 

 exceeded, but in the caterpillars of some families the three 

 front pairs of prolegs are wanting, those on the sixth and tenth 

 abdominal segments alone being retained. Such caterpillars 

 are frequently termed " loopers," because, the prolegs being 

 restricted to the hinder end of the body and the jointed legs 





FIG. 70. 



a, Pear Sawfly (Eriocampa limacina), female ; 6, larva (side 

 view ) ; c, larva with black, slimy coat (dorsal view) ; e, cocoon ; 

 /, resting larva (ventral view) ; g, pupa (ventral view), x 4. 

 d, leaves with larvae, natural size. From Mariatt, Ent. Circ. 26, 

 U.S. Dept. Agric. 



being just behind the head, the larva alternately bends and 

 stretches out its body as it crawls along a twig or leaf-edge. 



A caterpillar is an insect larva whereof crawling may indeed 

 be regarded as the characteristic mode of progression, and 

 caterpillars with a greater number of pairs of prolegs than in 

 the typical moth larva are distinctive of certain other orders 

 of insects. For example the saw-flies a well-marked group of 

 the Hymenoptera (see pp. 186-7) have caterpillars (Fig. 70) 



