332 



OUR HOUSEHOLD INSECTS 



a number of hooks, but the rest of the tube was thin, 

 flexible, and transparent. 

 Within the latter could be 

 traced four thin chitinous 

 bands, the representatives of 

 the two pairs of jaws, the man- 

 dibles and maxillae of the ordi- 

 nary insect's mouth. Thus we 

 have an arrangement resem- 

 bling in some degree that of 

 the mouth of the bed-bug and 

 other Hemiptera, a tubular 

 labium containing four setae, 

 the mandibles and maxillae. 

 During the process of the extru- 

 sion of this apparatus, the first 

 part to appear is the strong 

 base of the tubular labium, 

 but the hooks are at first in- 

 side the tube. They can, how- 

 ever, be everted, and by a con- 

 tinuance of the same process, 

 the membranous lining of the 

 tube is brought out and forms 

 * G& the long delicate sucker which 

 constitutes the greater part of 

 the proboscis. The labium 

 having been inserted into the 

 skin, say through a sweat 

 pore, the hooks become everted 

 and hold the proboscis steady 

 by clinging to the tissues 

 around. The piercing man- 

 dibles are then thrust out ; towards their tip they are 



FIG. in. Proboscis of Body- 

 Louse. (After Schiodte.) 



