342 



MANUAL OF ZOOLOGY. 



active condition of the pupa, this kind of metamorphosis is said 

 to be " incomplete." 



In some members of this section, however such as the 

 Dragon-flies the larva and pupa are aquatic, whereas the 

 imago leads an aerial life. In these cases (fig. 175) there is 

 necessarily a considerable difference between the larva and the 

 adult ; but the larva and pupa are closely alike, and the latter 

 is active. 



Section 3. Holometabolic Insects. These comprising the 

 Butterflies, Moths, Beetles, &c. pass through three stages 

 which differ greatly from one another in appearance, the meta- 

 morphosis, therefore, being said to be " complete." In these 

 insects (fig. 179) the "larva" is vermiform, segmented, and 



usually provided with loco- 

 motive feet, which do not 

 correspond with those of the 

 adult, though these latter are 

 usually present as well (fig. 

 179). In some cases the 

 larva is destitute of legs, or 

 is "apodal." The larva is 

 also provided with masticat- 

 ory organs, and usually eats 

 voraciously. In this stage of 

 the metamorphosis the larvae 

 constitute what are usually 

 called " caterpillars " and 

 " grubs." Having remained 

 in this condition for a longer 

 or shorter length of time, and 

 having undergone repeated 

 changes of skin, or " moults," 

 necessitated by its rapid 

 _ growth, the larva passes into 



the second stage, and be- 



Fig. 179. Metamorphosis of the Magpie- ' 



moth (Phaltena grossulariata). COniCS a "pupa. The inSCCt 



is now perfectly quiescent, 



unless touched or otherwise irritated ; is incapable of changing 

 its place ; and is often attached to some foreign object. This 

 constitutes what in the case of the Lepidoptera is generally 

 known as the "chrysalis," or "aurelia" (fig. 179). The body 

 of the pupa is usually covered by a chitinous pellicle, which 

 closely invests the animal. In some cases (e.g., in many Dip- 

 terous insects) no traces of the future insect can be detected 

 in the pupa by external inspection ; but in the Lepidoptera the 



