PHYLUM ARTHROPODA 



33 1 



usually tactile, olfactory, or auditory in function. They differ 

 widely in form and structure, as shown in Figure 250. Often 

 the antennae of the male differ from those of the female. 



The mouth-parts of insects are in most cases fitted either for 

 biting (mandibulatc) or sucking (suctorial). The cockroach pos- 

 sesses typical mandibulate mouth- 

 parts (Fig. 251) consisting of an 

 upper lip, the labrum, a lower lip, 

 the labium (B), a pair of jaws, the 

 mandibles (C), and a pair of auxil- 



I/.in 



FIG. 251. Mouth parts of a cockroach, 

 Periplaneta. A, ist maxilla. C, cardo ; 

 L.ex, galea; L.in, lacinia; Mxt, maxillary 

 palpus; St, stipes. B, labium or lower lip; 

 lettering as above. C, mandible (Md). 

 (From Sedgwick's Zoology, after Savigny.) 



FIG. 252. Mouth parts 

 of a mosquito, Culex memo- 

 rosus. H, hypopharynx for 

 piercing; Lb, lower lip or 

 proboscis; Lbr, upper lip; 

 Lt, labial palp; Md, mandi- 

 bles; MX, maxillae. (From 

 Sedgwick's Zoology, after 

 Becher.) 



iary jaws, the maxillae (-4). The labium and maxillae bear 

 jointed feelers or palps (Mxt) which function as sense-organs. 

 The labrum and labium hold the food while it is being mas- 

 ticated by the mandibles and maxillae. The mandibles of insects 

 that live on vegetation are adapted for crushing; those of 

 carnivorous species are usually sharp and pointed, being fitted 

 for biting and piercing. Suctorial mouth-parts are adapted for 



