22 



MOUTH OF INSECTS. 



Fig. 9. BUG. 



41. In the bugs (cimex), plant lice (aphis), 

 and other insects of the order Hemip'tera, the 

 sucking apparatus is composed of the same ele- 

 ments, but somewhat differently arranged. The 

 mouth is armed with a tubular and cylindical 

 beak, directed downwards and backwards (Jig. 

 9), and is composed of a sheath enclosing four 

 stylets ; the sheath (fig. 10, a) is formed of four 

 articulations placed end to end, and represents 

 the labium or lower lip ; &.t its base we perceive 

 an elongated, conical piece, which is analogous 

 to the labrum ; the stylets (b, c) which are in 

 the form of fine threads, stiff and dentate at the extremity, to 

 pierce the skin of animals or the substance of plants, are the 

 representatives of the mandibles and maxillae excessively elon- 

 gated. In the hemip'terae which live at the expense of other 



animals, the beak is gene- 

 rally very stout and fold- 

 ed in a semicircle under 

 the head. In those that 

 feed on the juices of 

 plants, it is, on the con- 

 trary, almost always 

 slender, and, when at 

 rest, applied against the 



l / 



a b c 



Fig. 10. BUCCAL APPARATUS OF AN HEMIP'TERA. 



inferior surface of the 

 thorax, betwixt the legs 

 (fig. 9). Its length is 

 sometimes so great as 

 to extend beyond the 

 posterior extremity of 

 the abdomen. 



42. In flies, the pro- 

 boscis or trunk, some- 

 times soft and retractile, sometimes horny and elongated, also 

 represents the labium or lower lip, and often has palpi at its base ; 

 a longitudinal groove on its upper surface lodges the stylets, 

 which vary from two to six in number; the mandibles, jaws, and 

 ligula of the tritores are analogous to them. Sometimes this trunk 

 acquires an enormous length, and sometimes, on the contrary, it 

 is scarcely visible. 



43. In butterflies (Papilio) which also feed on the liquid sub- 

 stances they find at the bottom of flowers, and have no necessity 

 for strong weapons to obtain them, there are no lancet-like stylets ; 



41. How is the sucking apparatus in Hemi'ptcra arranged? 



42. What are the peculiarities of the sucking apparatus of flies ? 



43. Describe tne sucking apparatus of butterflies. 



