218 



DIPTERA OR TRUE FLIES. 



(^Bomhi/Nu-^), others piercing mouths (Tubanus or the Gad-fly), 

 fig. 126 ; in the Warble-flies (CEstriihi^) the mouth is rudiment- 

 ary, the adults taking no nourishment. There is never a sting ; 

 flies wound by piercing with the mouth, but not, as is often 

 supposed, by stinging. The labium of the mouth (fig. 115, L/) 

 is greatly elongated, and forms a kind of gutter for the reception 

 of the lancet-shaped maxilla! and mandibles. The proboscis, 

 made up of the labium, &c., ends in a fleshy swollen tongue, 

 and is closed above by the labrum. There are no true labial 

 palpi, but the processes at the tip of the labium called lahdhi;. 

 are thought to represent them. The head is large, and united 

 to the thorax by a very short neck. The thorax is large and 

 compact, the prothorax closely united to the mesothorax, and 

 forming a thin collar or two lobes. The eggs of flies are 



usually oval or sj)indle- 

 shaped bodies, of a white 

 or black colour, sometimes 

 laid singly, at others in 

 groups. The larvae are 

 mostly white footless mag- 

 gots ; no true legs are ever 

 present. Thirteen segments 

 is the usual number present, 

 but in some fourteen may 

 be found (fig. 117, a). The 

 head may be horny and 

 complete, or may be re- 

 duced to a simple pair of hooks, the mandibles (fig. 132, d) ; 

 the body may be naked (fig. 117, a) or bristly (fig. 133, 7). 

 Most are terrestrial, but some have aquatic larvje — CuUcidir 

 (Mosquitoes), ChiroiioiiiiiJn' (J\Iidges) (fig. 116), and Url-ifalidir 

 (Eat -tailed Flies). The genera VolweUa, Tti'-Iiiiia, and Co7i02'!< 

 are parasitic in their larval stage on other insects ; the genera 

 Hyiwderma, Oasiropliilua, Qil^lruit, Lwilia, and Satropliaijns, 

 &c., on vertebrates. "When mature, dipterous larva? may or 



FlC!. 116.- 



-Plumed Gnat (Chironomus 

 plumos^ts). 



