STRUCTURE OF LARV^. 183 



2. Hexapodce, or tliose having six scaly legs, but being 



destitute of prolegs. The larvae of many Coleo- 

 ptera (fig. 15, larva of Trichius nobilis), and some 

 NeurojJtera. 



3. Apodce, or those destitute of legs and prolegs. Many 



Coleoptera, Hymenoptera (fig. 16, larva of wild bee), 

 gnats and tipulae (fig. 18, larva of Tipula), and the 

 flea (fig. 17, larva). 

 B. LarvcB ecapitatce, or those A^-ithout a distinct scaly head, 

 including the majority of dipterous insects (fig. 19, 

 larva of the flesh fly), some few of which are fm-- 

 nished with membranous tubercles serving as pro- 

 legs. 

 The head, in the generality of larvae, is covered with a cor- 

 neous case, often divided, by an impressed line running down 

 the middle of the face, into two lateral lobes ; its form is 

 more or less rounded, but it often assumes a triangular or 

 heart shape ; occasionally, as in the caterpillars of some but- 

 terflies, the two lobes are terminated by spines or tubercles 

 (fig.20). There are other variations in the appendages by which 

 this part of the body is distinguished. In the second section 

 above described, the head is generally retractile, membra- 

 nous, and variable in form, and destitute of eyes and anten- 

 nae, as well as of the ordinary parts of the mouth, which ap- 

 pears only to consist of a pair of hooks, or bristles, which 

 are incapable of either cutting or grinding ; the insect em- 

 ploys them not only to pierce the soft matters, upon the 

 juice of which it feeds, but also as claws whilst engaged in 

 locomotion. 



The head of larvae is generally provided with a pair of 

 short rudimental antennae, eyes, and organs of the mouth. 



The antennce (fig. 20, h) are placed near the base of the 

 mandibles ; they are for the most part totally unlike the an- 

 tennae of the perfect insect, although in the monomorphous 



