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- f 



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 



pup'a, chrysalis and cocoon understandingly. 



A luna cocoon cut open, showing tlie 

 Photo by M. V. SlingerLand. 



pupa. 



