INSECTS 



formed in the same way as are the antennae and the mouth 

 parts, that is, they are developed from the epidermis of 

 the corresponding larval legs; but, by reason of their in- 

 creased size, they are forced to bend upward against the 

 sides of the body of the pupa, and, when fully formed, 

 each is found to have only its terminal part within the 

 cuticular sheath of the leg of the caterpillar. 



From the thorax, the loosening of the cuticula spreads 

 backward over the abdomen, until at last the entire insect 

 lies free within the cuticular skin of the caterpillar. The 

 so-called prepupal period of the caterpillar, therefore, is 

 scarcely to be regarded as a truly larval stage of the in- 

 sect. It is still clothed in the larval cuticula, and retains 

 externally all the structural characters of the larva; but 

 the creature itself is in a first growth period of the pupal 

 stage, and may appropriately be designated a propupa. 



When the cuticula is separated from the epidermis all 

 over the body, it may be cut open and taken off without 

 injury to the wearer. The latter, now a propupa (Fig. 

 159 C), is then discovered to be a thing entirely different 

 in appearance from the caterpillar. It has a small head 

 bent downward, a thoracic region of three segments, and 

 a large abdomen. The head bears the mouth parts and a 

 pair of large antennae {A)it)\ the thorax carries the wings 

 {JVi, Wzi and the legs (L), which latter are much longer 

 than those of the caterpillar, but, being folded beneath 

 the wings, only their ends are visible in side view. The 

 abdomen consists of ten segments and has lost all ves- 

 tiges of the abdominal legs of the caterpillar (A, AL). 



Many important changes have taken place in the form 

 and structure of the head and in the appendages about 

 the mouth during the change from the caterpillar to the 

 propupa, as may be seen by comparing Figure 159 H, with 

 Figure 152. Most of the lateral areas of the caterpillar's 

 head (Fig. 152), including the region of the six small eyes 

 on each side, have been converted into the two huge eye 

 areas of the pupa (Fig. 1 59 H, E), which cover the develop- 



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