ANATOMY AND PHYSIOLOGY 



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from which the suctorial, or secondary type, has been derived, will be 

 considered first. 



Mandibulate Type. The labrum, or upper lip, in biting insects is a 

 simple plate, hinged to the clypeus and moving up and down; though 

 capable of protrusion and retraction to some extent. It covers the man- 

 dibles in front and pulls food back to these organs. On the roof of the 

 pharynx, under the labrum and clypeus, is the epipharynx; this consists 

 of teeth, tubercles or bristles, which serve in some insects merely to hold 

 food, though as a rule the epipharynx in mandibulate insects bears end- 

 organs of taste (Packard). 



FIG. 44. Mouth parts of a cockroach, Ischnoptera pennsylvanica. A, labrum; B, mandi- 

 ble; C, hypopharynx; D, maxilla; E, labium; c, cardo; g (of maxilla), galea; g (of labium), 

 glossa; /, lacinia; //>, labial palpus; m, mentum; mp, maxillary palpus; p, paraglossa; pf, 

 palpifer; pg, palpiger; s, stipes; sm, submentum. B, D and E are in ventral aspect. 



The mandibles, or jaws proper, move in a transverse plane, being 

 closed by a pair of strong adductor muscles and opened by a pair of weaker 

 abductors. The mandible is almost always a single solid piece. In 

 herbivorous insects (Fig. 45, A) it is compact, bluntly toothed, and often 

 bears a molar, or crushing, surface behind the incisive teeth. In car- 

 nivorous species (B) the mandible is usually long, slender and sharply 

 toothed, without a molar surface. Often, as in soldier ants, the man- 

 dibles are used as piercing weapons ; in bees (C) they are used for various 

 industrial purposes; in some beetles they are large, grotesque in form and 



