THE HIDDEN TYPE OF WING-GROWTH 123 



grub (Fig. 69 B) is often defined as sub-eruciform ; it shows, 

 like many beetle larvae a transition from the active, 

 armoured, long-legged campodeiform larva to the caterpillar 

 type. 



The typical caterpillar, as exemplified in the larva of a moth 

 or butterfly, has already been described with some detail in 

 the second chapter (pp. 56-63). In such a larva the firm, 

 thickened cuticle of the head capsule offers a strong contrast 

 to the thin flexible cuticle that covers the rest of the usually 



B 



FIG. 69. 



A, first-stage larva of Caddis-fly (Oxyethira), ventral view. B, third instar of same 

 (dorsal view), x 20. After Siltala, Zool. Jahrb. Suppl. IX. 



elongate, cylindrical and somewhat worm-like body. The 

 thorax carries three pairs of short, jointed, clawed legs rather 

 like those of the mining leaf-beetle grub already described in 

 this chapter (p. 112). But the distinctive feature of cater- 

 pillars among other insect larvae is to be found in the presence 

 of pairs of un jointed limbs or prolegs on certain segments of 

 the abdomen. In the moth-caterpillar described above there 

 are five pairs of such prolegs, the foremost on the third 



