INSECTS 



ing its development (Figs. 12, 13), and other examples of 

 a metamorphosis during the larval life might be given 

 from the other groups of insects. A larval metamorphosis 

 of this kind is known as hypermetamorphosis , and it shows 

 that the larva may be structurally diversified during its 

 growth to adapt it to several different environments or 

 ways of obtaining its food. 



The reader was given fair warning that the subject of 

 insect metamorphosis would become difficult to follow, 

 and even now, with its realization, the writer can not 

 assure him that the above analysis is by any means com- 

 plete or final. Much more might be said for which there 

 is no space here, and it is not likely that all entomologists 

 will accept all that has been said without a discussion, 

 and possibly some dissension. However, we have not 

 yet reached the end, for we have so far been dealing only 

 with the phase of metamorphosis that has produced the 

 nymph or the larva, and have only briefly touched upon 

 the reverse process which reconverts the creature into the 

 adult. 



The pupa unquestionably has the aspect of an imma- 

 ture adult. It has lost all the characteristic features of 

 the larva, and its organs are those of the adult in the 

 making. It has external wing pads, legs, antennae, com- 

 pound eyes. Its mouth parts are usually in a stage of 

 development intermediate between those of the larva and 

 those of the adult. Most of the pupal organs are useless, 

 since they are neither those of the larva nor entirely those 

 of the adult, and are not adapted to any special use the 

 pupa might make of them, except in a very few cases. 

 The pupa is, therefore, a helpless creature, unable to 

 eat, or to make any movement except by motions of the 

 body. It is usually said to be a "resting" stage, but its 

 rest is an enforced immobility, and some species attest 

 their impatience by an almost continuous squirming, 

 twisting, or wriggling of the movable parts of the body. 



It is evident that it must be an advantage to the pupa 



[250] 



