1 50 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



hinder thoracic segments. These wing-buds rapidly increase 

 in length, and by the time the developing grasshopper has come 

 to its adult size the wings are also full size and ready for use. 



During this growth and development of the young grasshop- 

 per, which requires several weeks for its completion, it molts 

 several times. This molting is the shedding of the chitinized 

 cuticle which covers the body. Before each molting takes 

 place, however, the skin cells have secreted a soft and colorless 

 new chitinized cuticle which, as soon as the outer old one is cast 

 off, becomes firm and colored, and takes its place. The young 

 grasshopper shows most of its changes in size and appearance 

 just after each molting. The wing-buds hardly seem to grow 

 between molting periods, but after each molting they may be 

 seen to be larger and more developed. 



Insects whose development is, in general, like that of the 

 grasshopper, that is, those which hatch from the egg in a 

 condition more or less resembling the parent except for size 

 and total absence of wings, are said to undergo a development 

 without metamorphosis or with incomplete metamorphosis. 

 While insects which, like the moths and butterflies, hatch from 

 the egg in a stage very different in appearance from that of the 

 parent, and in their development have to undergo extraordi- 

 nary changes in appearance and structural make-up to become 

 like the parent, are said to develop with metamorphosis, or 

 with complete metamorphosis. 



In insects with complete metamorphosis there is a curious 

 stage called the pupal or chrysalid stage which is interpolated 

 between the first or larval stage, which is that in which the 

 insect hatches, and the final or adult stage, the stage in which 

 the insect is sometimes called an imago. After the young 

 caterpillar has undergone a certain period of rapid growth and 

 increase of size, during which period it molts several times 

 but does not show any external changes making it any more 

 like its parent than it was at the beginning, it stops feeding 

 and changes into an inactive, non-feeding stage with its body 

 inclosed in a thick, firm, chitinized covering which is neither of 

 the shape of the larva nor of the imago. This is the so-called 

 pupal stage, and the insect in this condition is called a pupa. 



