310 SYSTEMATIC ARRANGEMENT 



body almost always elevated and curved in the form 

 of the letter S. Additional distinctive characters 

 might be mentioned, such as the form of the eyes, 

 which are pretty large in pseudo-caterpillars, and 

 placed one on each side of the head, while in true 

 caterpillars they are small almost invisible points 

 disposed in a circle ; but those already referred to 

 will suffice to distinguish the two tribes. 



The body of pseudo-caterpillars is generally com- 

 posed of twelve segments, but the incisures are in- 

 distinctly defined, and liable to be confounded with 

 the transverse wrinkles which thickly cover the 

 whole surface. Many of them are marked with 

 bright and varied colours, but the majority are of 

 one colour. In this respect they often undergo a 

 remarkable change after they have cast their last 

 skin, the colour becoming entirely unlike what it 

 was before, so that it is impossible to recognise the 

 same individual. This change, indeed, extends even 

 farther than to colour, for such kinds as are furnished 

 with tubercles or spines in their earlier stage, lose 

 them at their last moult and become smooth ; that 

 of the gooseberry species, for example, loses the 

 black tubercles which made the surface appear as 

 if shagreened. Like the flies they produce, these 

 larvae are sluggish and inactive, seldom moving from 

 the place where they have fixed themselves, unless 

 when requiring an additional supply of food. When 

 not engaged in feeding, or when apprehensive of 

 danger, they roll themselves into a circle, sometimes 

 with the tail elevated in the centre. The greater 



