10 INTRODUCTION. 



In the Bugs and their allies, which belong to the 

 order Bhyncota, we have another form of suctorial 

 mouth; here the labial palpi coalesce and form a jointed 

 beak or rostrum, which is a tube split down the front, 

 and enclosing two pairs of bristle-like organs, which are 

 really greatly altered forms of the mandibles and 

 maxillae ; by means of tliese sharp and fine needles the 

 Rhyncota pierce the tissues of animals or plants, and 

 feed on their juices. 



In the Fly kind the ligula is developed into a broad 

 fleshy organ or j^roboscis — whose form must be familiar 

 to the most careless observer — through which the insect 

 sucks up its food. In the Dlptera generally, as in the 

 common gnat, the labium consists of a long cylindrical 

 organ with a round top at the extremity ; along the 

 upper surface of the labium runs a groove which sheathes 

 the other organs of the mouth, viz., the mandibles, 

 maxillcTe, ligula, where it exists, and the labium ; all of 

 which are delicate cutting lancets, by means of which 

 the insect pierces its victim and sucks out the juices. 

 When you see this formidable array of miniature 

 lancets and javelins, you will not wonder at the rapidity 

 with which a gnat punctures your skin, and how im- 

 mediately you feel the wound. 



We now come to the second division of an Insect's 

 body, which as we have seen consists of three parts, 

 though from frequent amalgamation these segments are 

 not always distinguishable ; they constitute the thorax, 

 and bear the organs of motion, almost alwa3^s in insects 

 six legs, and generally four wings ; each leg is either firmly 

 attached to, or articulated with the thorax by a quasi 

 ball and socket joint, at the first joint, called the coxa 



