186 



AN INTRODUCTION TO ENTOMOLOGY 



Fig. 206. 

 Larva of 

 Platygaster 



(After Ganin.) 



outside of the body although still covered by the last larval cuticula ; 

 this period is the prepupal stadium. The prepupal instar differs 

 markedly from both the last larval one and from the 

 pupa; for after the shedding of the last larval cuticula 

 important changes in the form of the body take place 

 before the pupal instar is assumed. 



The pupa. The most obvious characteristics of the 

 pupa state are, except in a few cases, inactivity and help- 

 lessness. The organs of locomotion are functionless, 

 and may even be soldered to the body throughout their 

 entire length, as is usual with the pupae of Lepidoptera 

 (Fig. 207). In other cases, as in the Coleoptera (Fig. 

 208) and in the Hymenoptera, the wings and legs are 

 free, but enclosed in more or less sac-like cuticular 

 sheaths, which put them in the condition of the pro- 

 verbial cat in gloves. More than this, in rnost cases, the legs of the 

 adult are not fully formed till near the end of the pupal stadium. 



The term pupa, meaning girl, was applied to this instar by Linnaeus 

 on account of its resemblance to a baby that has been swathed or 

 bound up, as is the custom with 

 many peoples. 



Although the insect during the pupa] 

 stadium is apparently at rest, this, from a 

 physiological point of view, is the most 

 active period of its postembryonic exist- 

 ence; for wonderful changes in the struc- 

 ture of the body take place at this time. 



In the development of a larva the primitive form of the body has been greatly 

 modified to adapt it to its peculiar mode of life; this sidewise development results 

 in the production of a type of body that is not at all fitted for the 

 duties of adult life. In the case of an insect with incomplete meta- 

 morphosis, the full grown naiad needs to be modified comparatively 

 little to fit it for adult life; but the change from a maggot to a fly, 

 or from a caterpiller to a butterfly, involves not merely a change 

 in external form but a greater or less remodeling of its entire 

 structure. These changes take place during the period of apparent 

 rest, the prepupal and pupal stadia. 



Fig. 208 The chrysalis. The term chrysalis is often applied to 



Pupa j-^g p U pgg o f butterflies. It was suggested by the golden 

 beetle. spots with which the pupae of certain butterflies are 



ornamented. 



Two forms of this word are in use: first, chrysalis, the plural of 

 which is chrysalides; and second, chrysalid, the plural of which is 



Fig. 207. Pupa of a moth. 



