Insects and their world 



Fig. 35. A hawk-moth. Order Lepidoptera 



thorax, also have false legs (prolegs, or pseudopods) on some at least of 

 the abdominal segments. Caterpillars (also called eruciform larvae. Fig. 

 33c) are polypod larvae, and are found in butterflies and moths 

 (Lepidoptera), scorpion flies (Mecoptera) and sawflies, (Hymen- 

 op XERA-Symphyta). The prolegs are rather shapeless swelUngs, which 

 in Lepidoptera, but not in sawflies, are equipped with tiny hooks 

 {crochets). 



Larvae that have no legs at all (apodous, Fig. 33d) generally live among 

 a mass of food-material. Though legless, they are not necessarily 

 immobile; maggots of flies, for example, can move quickly and pur- 

 posefully by wriggling, and sometimes by jumping (see Chapter V). 

 They are always evolved from ancestors that did have legs, and distinct 

 vestiges of these may sometimes be visible. Apodous larvae are found 

 in several families of beetles ; among bees and wasps where the parent 

 inseas provide food for the larvae; and in all groups of flies and fleas. 



When an insect starts hfe as one type of larva, and later changes to a 

 different type, with different feeding habits, this is called hypermeta- 

 morphosis. 



Pupae 



The larvae of holometabolous insects are so different from the 

 adults — and what is more, they make no progress towards adult struc- 



56 



