CARNIVOROUS INSECTS 



121 



HYPQPHXRYNX HLABIOM. 



usually benevolent person could resist the chance of immolating 

 the aggressor, a particularly easy matter as it happens. Bot- Flies 

 make up a family with reduced mouth-parts, and, though not blood- 

 suckers, are more dangerous to horses and stock than Gad- Flies 

 and the like, for they lay their eggs upon domestic animals, upon 

 or inside which the larvae, when they hatch out, become parasitic. 

 Details will be given when the question of parasitism is discussed. 

 GNATS AND MIDGES. Few animals cause more annoyance 

 and discomfort than the Gnats, Mosquitoes, Sand-Midges, and, 

 to a less extent, true Midges, which abound in all parts of the 

 the world, and have been made notorious by the lurid descriptions 

 of innumerable travellers. Mosquitoes and Gnats (Culicidce) are 

 one and the same thing; a familiar British species is the Common 

 Gnat (Culex pipiens\ which possesses 

 typical piercing mouth -parts (fig. 392). 

 The labrum is a long, pointed structure, 

 with its grooved under side forming a 

 canal along which blood is conducted to 

 the mouth. Both mandibles and first 

 maxillae are lengthened out into pierc- 

 ing bristles, by which a wound can be 

 inflicted, and which are enclosed in a 

 sort of sheath formed by a modification 

 of the labium. It should further be 

 noted that a long, pointed tongue (hypo- 

 pharynx), upon the end of which the 

 ducts of the salivary glands open, is 

 enclosed in this sheath, from the back 

 part of which it grows out. Sand- 

 Midges (Simuliid&\ poorly represented in Britain, are most 

 abundant in the tropics, and though much smaller than Gnats, 

 are even more noxious, their bite being particularly virulent. 

 The name of " Sand-Fly" is commonly given to them. Midges 

 (Chironomida} are minute insects, for the most part not adapted 

 for blood-sucking, though to this there are exceptions, as in the 

 case of the common Black Midge (species of Ceratopogon), which 

 is one of our summer pests in the country. In all these cases it 

 is the female only that feasts on blood, and her mouth-parts are 

 therefore adapted for piercing and sucking, conforming more or 

 less closely to the type described for the Gnat. 



LABIAL PAITP. 



Fig. 392. Mouth parts of a Female Gn 

 ^ Culex pipens], greatly magnified 



