186 THE BOOK OF NATURE STUDY 



different shape at the extreme hind end. The claspers are non- 

 jointed, fleshy outgrowths, and are furnished with rows of little 

 hooks round their soles for securing firm foothold. 



All lepidopterous larvae, except a very few aberrant legless 

 forms, have six true legs upon the thorax ; also they never have 

 claspers upon the first two abdominal segments, but the condition of 

 the other abdominal segments varies in different sub-groups, the 

 number of claspers being often much reduced, e.g. in the " Looper " 

 caterpillars (Geometers). The fact that in Lepidoptera the first 

 two segments of the abdomen are always destitute of claspers 

 is important, for the larvae of certain sawflies (Hymenoptera) 

 are very similar to true caterpillars in appearance, but may be 

 distinguished by the possession of a pair of claspers upon the 

 second abdominal segment. 



On the sides of the body are nine pairs of spiracles. These 

 are moderately conspicuous openings in the yellow lateral line ; 

 they occur one pair on the first thoracic, and a pair on each 

 of the first eight abdominal segments. Traces of such openings 

 can sometimes be seen on the other thoracic segments, but they 

 are not now functional. 



During larval life immense stores of fat are accumulated within 

 the body, for this is the main feeding period, comparatively 

 small quantities of food being consumed by the butterfly itself. 

 Indeed, there are many lepidopterous imagines which are quite 

 incapable of taking food. 



Pupation. When full fed the larva quits its food plant, and, 

 after a short journey over the ground, climbs up a wall or fence 

 or tree trunk, and there spins once again a little silken platform 

 similar to that already constructed at each moult, but in addition 

 places a girdle of silk round the middle of the body, attaching 

 each end to the vertical surface selected. The larva rests with 

 its head uppermost, though occasionally the body is horizontally 

 placed, and with the hindmost claspers securely attached by their 

 hooks to the silken platform. During this period of rest the 

 length of the animal becomes decidedly less. After some hours 

 the skin cracks open in the dorsal region of the thorax, and by 

 a series of spasmodic jerks and wriggles is worked off down towards 

 the tail. The form now assumed is known as the chrysalis or 



