130 INSECT TRANSFORMATION 



of short, stiff, un jointed feelers, and very strong toothed man- 

 dibles, adapted for the root-feeding habits of these grubs. The 

 maxillary lobes are also strongly toothed, and in some grubs 

 belonging to this group maxillulae have been detected. 1 A 

 noteworthy feature of the larva is the presence of a strong 

 chitinous plate on either side of the pharynx, strengthening the 

 wall of that organ and affording support to the jaws. Another 

 feature of great importance is the absence of the usual series of 

 lateral spiracles and the restriction of these air-openings to a 

 large pair at the tail-end of the body, somewhat on the dorsal 

 aspect, where they appear as conspicuous circular plates 

 surrounded by outstanding finger-like papillae (Fig. 74). 

 Ventral to this spiracular area is the anus (A) surrounded by 



FIG. 74. TAIL-END OF LARVA OF Tipula paludosd. 



Showing spiracles surrounded by papillae : dorsal (DP) : lateral 

 (LP) ; ventral (VP) ; A, anus ; 'AP, anal papilla. x 18. After 

 Rennie, Ann. Appl. Biol. III. 



lobes, a pair of which, protrusible as "anal prolegs", assist 

 in the locomotion of the grub. 



From such grubs we may pass to consider one of the type 

 characteristic of the great majority of the order of the two- 

 winged flies the maggot of a house-fly 2 or a blue-bottle 3 

 (Fig. 75). Here we find the greatest divergence between the 

 perfect insect and the larva, for the former may perhaps be 

 regarded as the most specialized in structure of all winged 

 insects owing to the high elaboration of some organs and the 

 reduction or disappearance of others, while the latter is not 



1 S. Bengtsson : " Bidrag till Kannedomen an Larven of Phalacrocera 

 replicata". Act. Reg. Soc. Physiog. Lund. Univ. Arsskr. XXXIII. 1897. 



2 C. Gordon Hewitt : " The House-fly ". Cambridge, 1914. 



3 B. T. Lowne : " The Anatomy, Physiology, Morphology and Develop- 

 ment of the Blow-fly ". London, 1890-95. 



