ENTOMOLOGY 



rentiation, the mouth parts are of fundamental importance to 

 the systematist, particularly for the separation of insects into 

 orders. Most of the orders fall into two groups according 

 as the mouth parts are either biting (mandibulate) or sucking 



FIG. 43- 



Antennae of mosquito, Culex pipiens. A, male; B, female. 



(suctorial). Collembola and Hymenoptera, however, com- 

 bine both functions ; Diptera, though suctorial, exhibit various 

 modifications for piercing, lapping or rasping; Thysanoptera 

 are partly mandibulate but chiefly suctorial; and adult Ephe- 

 merida and Trichoptera have but rudimentary mouth parts. 



The mandibulate orders are Thysanura, Collembola (pri- 

 marily), Orthoptera, Platyptera, Plecoptera, Ephemerida 

 (rudimentarily in adult), Odonata, Neuroptera, Mecoptera 

 and Coleoptera. 



The mouth parts of an insect consist typically of labrum, 

 mandibles, maxilla, labium and hypopharynx (Fig. 44), 

 though these organs differ greatly in different orders of in- 

 sects. The mandibulate, or primary type, from which the 

 suctorial, or secondary type, has been derived, will be consid- 

 ered first. 



Mandibulate Type. The labrum, or upper lip, in biting 



