STRUCTURE, GROWTH AND ECONOMICS OF INSECTS 



Ephemerida, and Coleoptera; suctorial, present in the Hemiptera, 

 Lepidoptera and Diptera; and mandihulate-suctorial in the Hymen- 

 optera. The mouth-parts with the exception of the labrum are true 

 appendages of the head segments, and in the embryo arise in exactly 

 the same way as the legs and antennas. 



Mandibulaie Mouth-parts. — The mouth-parts of biting insects 

 consist of: the labrum or upper lip attached to the clypeus (Figs. 

 2 and 4) ; a pair of mandibles, simple and unjointed, articulated to the 

 gencB; a pair of maxillcB, each made up of a basal one-, or two-jointed 



p.m. 



Fig. 5. Fig. 6. 



Fig. 5. — Mandible of cricket. A, Cephalic view; B, caudal view; mh., mem- 

 brane; mc.i, mc.2, adt., adductor muscles; abt., abductor muscles. 



Fig. 6. — Maxilla of cricket. C.i, C.2, Cardo; Mb.2, base of maxilla; pf., pal- 

 pifer; st., stipes; p.m., maxillary palpus; g., galea; /., lacinia. 



hinge segment, the cardo, a central segment the stipes which bears the 

 palpifer to which the typically five-jointed palpus is attached, and two 

 distal lobes the outer of which is termed the galea and the inner the 

 lacinia (Fig. 6). The labium or lower lip, composed of a broad basal 

 part, the submenfum, joined to the gula, a mentum or central portion, 

 a pair of jointed palpi attached to the mentum by means of a small 

 sclerite, the palpiger, and a median part which may be simple or 

 slightly bilobed in which case it is termed the ligula, or it may consist 



