SLIME SLUGS, MYRIAPODS AND INSECTS 147 



also a pair of maxillary palpi, as long as the beak in both males 

 and females of some mosquitoes, but shorter in the females of 

 most species. 



Mouth -parts of House-fly. -The mosquitoes belong to the 

 order of two-winged flies, but their mouth-parts cannot be 

 taken as typical of the order. A house-fly, for example, 

 has a mouth very different in make-up. The labium is a 

 fleshy proboscis expanded at the tip to form a special lapping 

 and rasping organ, and there are no mandibles or maxillae, 

 at least in functional condition. There is one pair of short 



FIG. 63. Mouth-parts of the house-fly, Musca domestica. lb., Labrum; 

 mx. p., maxillary palpi; //., labium; la., labellum. 



palpi which are usually called the maxillary palpi, although 

 they may really belong to the labium. The house-fly takes 

 up food either by lapping liquids with the broad tongue-like 

 end of its proboscis, or by rasping off bits of solid food, pouring 

 out saliva over them and then lapping them up as a fluid 

 mixture. The end of the proboscis, which is called the labellum, 

 is very elaborately contrived and furnished with ridges for 

 rasping and special muscles for folding and unfolding. 



Mouth-parts of Butterflies and Moths. The sucking tube 

 of the butterfly or moth is still another very different type of 

 mouth. There is no labrum, mandibles nor labium, or only 

 rudiments of them. But the maxillae are developed into a 

 pair of long, slender, coiling pieces or processes which can be 

 held together in such a way as to form by means of their 

 grooved inner faces a perfect tube, long, slender and flexible. 

 With this tube they suck out nectar from the nectaries 



