l62 



THE INSECT WORLD. 



We will now see how the insect deHvers itself from the last skin. 

 To quit the pupa case is not so laborious an operation as it was for 

 the same insect to quit the caterpillar's skin. This is because the 

 pupa case is drier ; it does not adhere to every part of the body, and 

 is brittle. Those insects which are enclosed in a cocoon free them- 

 selves of the pupa envelope in the cocoon itself. To witness the 

 last operation, the cocoon may be opened, and the pupa drawn out 



Fig. i28.-C:hrysalisofthe Large Tortoise-shell Butterfly [Vanessa ^olyckloros) whose differei 



parts have been opened before they were fastened down. 



{a, wings ; b b, antennae ; t, trunk, or proboscis.) 



of it with care. If it is then placed in a box, the metamorphosis 

 may be observed. To study this last evolution more at his ease 

 Reaumur covered a large extent of the wall of his study with pup 

 of the Vajiessa polyc/iioros and other species. i 



When the parts of the body of the insect have attained a certaia 

 degree of solidity within the envelope, it has no great difficulty ii 

 makmg the thin and friable membrane which surrounds it split -^ 

 different places. If it even distends itself or moves, a small openiL 

 will be made m the dried skin. If the movements persist, tkj 



pf ■J'TJ'' ^^""^ S^""^ f ^'^^ ^"'^'^' '"^"^^^^ i^ this state a variable time-the Sma 

 iiggar [Bombyx lanestrts) sometimes as many as seven years.— Ed. 



