STRUCTURE AND DEVELOPMENT OF INSECTS 



25 



but hardens and forms a case called a puparium within which 

 the pupal stage is passed. 



The typical pupa (Fig. 15, c, d) of a butterfly or moth re- 

 sembles neither the adult insect nor the larva, is of a more or 

 less oval shape, with the wings and antenna? tightly folded at 



Fis. 16. Incomplete metamorphosis of a bug (Brachymena ^-pustulata) : 

 a, eggs; b, adult bug; c, different stages of young bugs or nymphs. 



the sides, the legs drawn up snugly together under them, and the 

 head and mouth-parts bent upon the breast, or sternum, though 

 all of these parts are not always recognizable, the legs and mouth- 

 parts being sometimes lacking. Gradually the adult insect 

 develops, and at last the pupal skin is broken open and the airy 

 butterfly emerges to enjoy a short life and perpetuate the species. 



