THE STUDY OF INSECT LIFE u 



different insects, and frequently having an ad- 

 hesive pad or sucking disk between them. 

 During the larval stage of the insect's life, the 

 abdomen may bear upon its under surface 

 certain pairs of clasping or sucker feet, by 

 means of which the insect retains its hold on 

 the surface of the foliage on which it feeds ; 

 but in the adult (imago) stage there are no 

 paired limbs upon the abdominal segments, 

 the posterior abdominal segment bearing the 

 genital organs, and such appendages as the sting 

 and ovipositor, all being subject to great modifi- 

 cation of form. 



On examining the internal anatomy of an 

 insect, the alimentary canal will be found to con- 

 sist of the fore-, mid-, and hind-gut. The length 

 and structure of the alimentary canal varies 

 considerably in different insects, diet playing an 

 important part in the modification of its size and 

 structure. For instance, the gullet, which is 

 included in the fore-gut, may be swollen into a 

 species of crop, or have an appended pouch 

 forming the so-called sucking stomach, or be 

 adapted as a gizzard with hard grinding plates. 

 The mid-gut is glandular, absorptive, and diges- 

 tive, its length frequently varying inversely with 

 the nutritive and digestible qualities of the food 

 of the insect. The general function of the hind- 

 gut, from which the excretory tubes or Malpighian 

 vessels arise, is absorptive. It is frequently 

 coiled, and in the region of the rectum is associ- 

 ated with certain glands. The nervous system 

 is composed of a double chain of nervous matter 

 extending from head to tail, and having two 



