ANATOMY OF INSECTS EXTERNAL 



used, and their structure is so constant and characteristic in different 

 groups as to furnish one of the best means of classification. Most 

 of tire orders possess 

 one of the two main 

 types of mouth-parts, 

 - those formed for 

 biting (mandibulate), 

 and those formed for 

 sucking (suctorial, or 

 haustellate). The bit- 

 ing type, as found in ^ ^ 

 the grasshopper, is the 

 more typical, and will 

 therefore be discussed 

 first. 



The labrum, or up- 

 per lip, is a simple 

 flap projecting over 

 the upper part of the 

 opening of the mouth 

 and covering the man- 

 dibles. It is hinged on 

 the posterior margin, but otherwise is free and may be slightly 

 protruded or retracted, to aid in bringing food to the mandibles. 



FIG. ii. Mouth-parts of grasshopper, typical biting 

 or mandibulate mouth-parts 



Ibr, labrum, or upper lip ; md, mandible ; mx, maxilla ; lab, 



labium, or lower lip ; /, palpus ; g, galea ; /, lacinia ; lig, 



ligula ; hyp, hypopharynx 



FIG. 12. Various forms of mandibles 



A, grasshopper (Melanoplus) ; B, tiger beetle (Cicindelidae) C, bee (Apis) ;" D, Onthopha- 

 gus; E, lace-winged fly (Chrysopa) f-I, soldier termites. (After Hagen, from Folsom) 



The mandibles, or jaws, are composed of a single toothlike 

 piece and move in a transverse plane. The form of the mandibles 



