ECONOMIC ENTOMOLOGY 



of a distinct pair of inner and outer lobes termed respectively the 

 glosscB and paraglosscB (Figs. 3 and 7). A comparison of Figs. 6 and 7 

 will show a perfect homology between the segments of the maxillae 

 and of the labium. The hypopharynx or tongue united to the base 

 of the labium; and the epipharynx under the labrum and clypeus 

 bearing teeth, tubercles or bristles (Figs. 8 and 9). 

 These parts diflfer greatly in the different orders. 

 Suctorial Mouth-parts. — The suctorial mouth-parts of flies, bugs, 

 moths and other insects have been evolved from the primitive mandibu- 

 late type. In some forms such as the squash bug and mosquito all 

 of the mouth-parts are present and it is comparatively easy to identify 



them with the corresponding append- 

 ages of the biting insects. In other 

 forms, however, the house-fly for ex- 

 T^^^^PSrf ample, some of the mouth-parts are 

 missing or fused with others, and it is 



Fig. 7. Fig. 8. 



Fig. 7. — Labium of cricket, hyp., Hypopharynx; gl., glossa; 

 pi., labial palpus; pg., palpiger; m., mentum; sm., submentum. 

 Pig. 8. — The labrum-epipharynx of cricket. 



I., paraglossa; 



more difficult to determine their homology. The following descrip- 

 tions will illustrate the typical arrangements in the three chief purely 

 suctorial orders of insects. Three types occur in the Diptera — the 

 piercing type, with all the mouth-parts present, e.g., the female horse 

 fly and mosquito; the piercing type with some of the mouth-parts 

 missing or fused, e.g., the horn flies and stable flies, and the non- 

 piercing type such as the house-fly and blow flies in which the beak 

 is used for rasping and sucking. 



Mouth-parts of the Horse Fly (Tabanid). — The mouth-parts of the 

 female are composed of six blades loosely ensheathed in the labium 



