How they perform the primary functions 



Fig. 34. A clothes-moth. Order Lepidoptera, with scaly wings 



Larvae^ on the other hand, have an enormous range of shape and 

 size. Those of parasitic insects hatch from the egg to find themselves 

 surrounded by unlimited food, and need only the simplest kind of 

 organs to feed upon it. Indeed in such a situation there is no need for 

 the egg to have a large store of food as yolk, and the larvae, in effect, 

 hatches prematurely while still an embryo. 



The larvae of other holometabolous insects fall into two general 

 groups : those with legs, and those without. This is not quite as casual 

 a distinction as it might seem. The possession of legs is related to the 

 activity of the larva, and this again to its feeding habits. Very active, 

 quick-running larvae, hke those of many beetles, may have three pairs 

 of well-developed segmented legs on the thorax, but no abdominal 

 appendages, except at the tip (Fig. 33a)uhese are known as campodeiform 

 larvae, because they look like the genus Campodea of the Order 

 Thysanura. The fat, grub-like beetle larvae that are found in soil, 

 decaying wood, dead leaves, and so on, are called scarabaeiform, because 

 the well-known chafers (Scarabaeidae) have larvae of this type. These, 

 again, have three pairs of legs on the thorax, and none on the abdomen 

 (Fig. 33b). 



These two types of larvae are called oligopod (i.e. 'few legs'). Polypod 

 larvae (i.e. 'with many legs'), in addition to the segmented legs of the 



55 



