8 



ECONOMIC ENTOMOLOGY 



the tip into a pair of soft cushion-like lobes, the oral lobes or lobelia 

 (Fig. 12). The under sides of these lobes are traversed by a large 

 number of open channels, the pseudo-trachece, which open into the mouth 

 situated near the middle; the greater portion of this proboscis is the 

 modified labium. Lying above the grooved labium is the small spade- 

 like labrum which may be raised by a pin. Near the base of the probos- 

 cis and above the labrum are two small lobes, the maxillary palpi, the 

 maxillae being fused with the fleshy base of the labium. 



Fig. 10. — Head and mouth-parts of a horse-fly (Tabanus). The maximum 

 number of parts is retained, but the piercing structures are distinctly blade-hke. 

 Dipteron type, second subtype. A, Side view of head showing: i, antenna (brachy- 

 cerous); 2, compound eye; 3, labium; 4, labella; 5, maxillary palpus; B, piercing 

 structures exposed, labium removed; 6, mandibles; 7, maxillae; 8, hypopharynx; 9, 

 labrum-epipharynx. {After Herms.) 



Mouth-parts of the Stable Fly. — The proboscis is awl-shaped and is 

 adapted for both piercing and sucking (Fig. 13). It projects forward 

 horizontally and has a prominent elbow. The labella are small and 

 are provided with cutting and adhesive structures. Lying above and 

 within the folds of the proboscis or labium are two unequal, sharp heavy 

 bristles, the larger representing the labrum and the smaller the hypo- 

 pharynx. The maxillary palpi are not so large as those of the house- 

 fly. The palpi of the Horn Fly are longer and more flattened, and 

 the proboscis is plumper and not thrown so far forward. 



Mouth-parts of the Squash Bug. — -The mandibles and maxillae are 

 reduced to needle-like structures, the two innermost (the maxillae) are 

 united to form a piercing tube. The needles fit in the groove of the 



