6 



SCHOOL ENTOMOLOGY 



maxilla is a finger-like structure called a palpus. The 

 labium bears a similar pair of palpi. In the insect which 

 has its mouth-parts modified for sucking these parts will 



not be so readily recognized 

 and some of them may be ab- 

 sent. Most of them may be 

 identified by their relative posi- 

 tion at the point of attachment 

 to the head, as this never varies. 

 The part of the epicranium 

 that lies between the eyes and 

 the base of the labrum is de- 

 signated as the front. To either 

 side of the front are the cheeks 

 or gence. The highest point of 

 the epicranium, just at the limit 

 of the front, is the vertex. Back 

 of the vertex, eyes and cheeks 



lies the occiput. This fits into the front or anterior margin 

 of the thorax. 



7. The Thorax. The thorax of an insect is composed, 

 always, of three segments. The first of these is the pro- 

 thorax, the middle one is the mesothorax, and the last 

 or posterior segment, is the metathorax. Each of these 

 bears one pair of legs (in the perfect insect or adult). 

 The front wings, where there are two pairs, are borne on 

 the mesothorax, and the second pair of wings is attached 

 to the metathorax. Where one pair of wings only is pres- 

 ent it is the front pair. 



The top of a thoracic segment is called the notum of 

 that segment, the side is the pleuron and the bottom plate 

 the sternum. 



An insect's leg is composed of several joints or seg- 



FIG. 3. Mouth-parts of 

 Sucking Insect, (true bug). 



a, labrum; b, labium; c, man- 

 dibles; d, maxillae. 



