THE METAMORPHOSIS OF INSECTS 



185 



prolegs are wanting. This type is quite characteristic of the lar\^£e 

 of the Scarabaeidag, hence the name ; but it occurs in other groups 



of insects. 



The movements of these larvae are 



slow; most of them live in the ground, 



or in wood, or in decaying animal or 



vegetable matter. 



Vermiform. — Those larvae that are 



more or less worm-like in form are 



termed vermiform. The most striking 



features of this type are the elongated 



Fig. 204. — Larva of Melolontha form of the body and an absence of 



vukaris (After Schiodte). locomotive appendages (Fig. 205). 



Naupliiform. — The term naupliiform is applied to the first instar 



of the larva of Platygaster (Fig. 206), on account of its 



resemblance to the nauplius of certain Crustacea. 



The prepupa. — Usually the existence of an instar 

 between the last lan.^al one and the pupal instar is not 

 recognized. But such a form exists; and the recogni- 

 tion of it becomes important when a careful study is 

 made of the development of holometabolous insects. 

 As is shown later, during larval life the develop- 

 ment of the wings is going on within the body. As 

 the larva approaches maturity, the wings reach an 

 advanced stage of development within sac-like invagi- 

 nations of the body-wall. Near the close of the last 

 larval stadium the insect makes preparation for the 

 change to the pupa state. Some form a cell within 

 which the pupa state is passed, the larvae of butter- 

 flies suspend themselves, and most larvae of moths spin 

 a cocoon. Then follows a period of apparent rest before 

 the last larv^al skm is shed and the pupal state assumed. 

 But this period is far from being a quiet one; within 



the apparently motionless body important changes p^ ^^ 



take place. The most easily observed of these Larva of a 

 changes is a change in the position of the wings, crane-fly. 

 Each of these passes out through the mouth of the sac in which it has 

 been developed, and lies outside of the newly developed pupal cuti- 

 cula, but beneath the last larval cuticula. Then follows a period of 

 variable duration in different insects, in which the wings are really 



