Insect Study 



39 



Full-grown caterpillar of the litna moth. 

 Photo by M. V. Slingerland. 



by it. This skin is so 

 firm that it cannot stretch 

 to accommodate the in- 

 creasing size of the grow- 

 ing insect, thus from time 

 to time it is shed. But 

 before this is done, a new 

 skin is formed beneath 

 the old one. After the 

 old skin bursts open and 

 the insect c'rawls forth, 

 the new skin is sufficiently 

 soft and elastic to allow 

 for the increase in the 

 size of the insect. Soon, 

 the new skin becomes 

 hardened like the old one, 

 and after a time, is shed. 

 This shedding of the skin 



is called molting. Some insects shed their skins only four or five times 

 during the period of attaining their growth, while other species may molt 

 twenty times or more. 



After the larva has attained its full growth, it changes its skin and its 

 form, and becomes a pupa. The pupa stage is ordinarily one of inaction, 

 except that very wonderful changes take place within the body itself. 

 Usually the pupa has no power of moving around, but in many cases it 

 can squirm somewhat, if disturbed. The pupa of the mosquito is active 

 and is an exception to the rule. The pupa is usually an oblong object 

 and seems to be without head, feet or wings; but if it is examined closely, 

 especially in the case of 

 butterflies and moths, the 

 antennae, wings and legs 

 may be seen, folded down 

 beneath the pupa skin. 



Many larvae, especially 

 those of moths, weave 

 about themselves a cover- 

 ing of silk which serves to 

 protect them from their 

 enemies and the weather, 

 during the helpless pupa 

 period. This silken cover- 

 ing is called a cocoon. 

 The larvae of butterflies 

 do not make a silken 

 cocoon, but the pupa is 

 suspended to some object 

 by a silken knob, and in 

 some cases by a halter of 



silk, and remains entirely naked. The pupa of a butterfly is called a 

 chrysalis. Care should be taken to have the children use the words- 

 pupa, chrysalis and cocoon understandingly. 



A lima cocoon cut open, slwwing the pupa. 

 Photo by M. V. Slingerland. 



