HOW INSECTS GROW 



251 



stage is the adult (Figs. 165, 171). With a few insects 

 there is no visible egg stage, as the young are born alive. 

 This is the case with the plant-lice. The larval stage 

 is the growing stage in every insect's life. If it is not 

 well fed, the adult insect coming from it will be smaller 

 in size than usual. The pupa, or pupal stage, occurs only 

 among insects in which the larva is very different from the 

 adult. It is purely a trans- 

 formation stage, and is one 

 of the most wonderful facts 

 in the life of any animal. 



Transformation from cater- 

 pillar to butterfly. When 

 the butterfly caterpillar has 

 become fully grown, it ceases 

 to feed and seeks some pro- 

 tected spot in which to trans- 

 form. For a time it seems 

 to shrink or shrivel as though 

 about to die. The most won- 

 derful thing, perhaps, is that 

 through all the vital changes 

 that take place within its 



body during this period it Courtesy U.S. Bur. Entomology 



r FIG. 1 66. BREEDING CAGE 



does not die. After a few Cage used to confine insects when study- 

 days, the caterpillar sheds ing their habits, 

 its larval skin and becomes the pretty, shining chrysalis, 

 or pupal case, of the butterfly. This is generally attached 

 to some twig or stem. The surface is marked with 

 delicate lines which really indicate the outlines of the 



