that spread Disease. 15 



within it a labrum, a hypopharynx, a pair of maxillae, and a 

 pair of mandibles. The labrum of mosquitoes is generally 

 long, slender, and pointed, and grooved beneath for the re- 

 ception of the hypopharynx, which lies immediately below, 

 and has its apex more or less wrapped round by the inflected 

 margins of the labrum. The two maxillae are long, and each 

 tapers gradually to the apex, which is provided with fine teeth. 

 The two mandibles are of the same length as the maxillae, and 

 their tips partially embrace the apices of the maxillae. All these 



FIG. 3. A MOSQUITO THAT SPREADS MALARIA, 

 Anopheles maculipcnnis, female, X 4. 



parts when at rest lie concealed in the labium, which is deeply 

 channelled for their reception, and is furnished at its extremity 

 with two fleshy lobes, the labella. The labium does not enter 

 the skin of the animal attacked, but bends back beneath the 

 body of the insect, the labella acting as guides to support the 

 piercing organs. 



In male gnats the mandibles are absent, and the maxillae are 

 very short, and cannot be used as piercing instruments. The 

 maxillary palps of the male Culex are as long as the proboscis, 



