352 



CHARACTERS OF INVERTEBRATE ANIMALS 



parts of the Cockroach both in appearance and use, can be 

 compared with them part for part. The narrow upper lip 

 is pointed, and below it are the mandibles, but these, instead of 

 being cutting-jaws, are long piercing stylets, grooved along their 

 inner sides in such a way as, when applied together, to form a 

 double tube down the lower half of which saliva can pass to the 

 object pierced, while juices can travel along its upper half to the 

 mouth. Outside, and close to the mandibles, are the first maxillcB 



in the form of two more 

 stylets devoid of palps. 

 The four stylets to- 



Fig. 203, — A typical Bug {Capsus) 

 ft, i. First two segments of thorax ; c, d, homy 

 part of wing-covers; s,_/i membranous part of 

 wing-covers; ff, antennae; k,k,k, legs; 1, eyes; 

 sch, top of head. 



Fig. 204, — Cicada, seen 

 from below 



gether constitute an efficient piercing organ which can be pro- 

 truded or drawn back at will by the action of special muscles, 

 and it also forms a channel along which fluids can be conducted 

 to the mouth, as just explained. The second maxillce, including 

 their palps, are fused together into a sheath for the piercing mouth- 

 parts. In most cases the adult condition is attained without any 

 large amount of metamorphosis. 



The order is conveniently divided into two sub-orders; i.e. 



1. Homoptera, in which the two pairs of wings are similar; and 



2. Heteroptera, in which they are unlike. 



I. Homoptera. — These all live upon the juices of plants, 

 and their fore-wings are of uniform texture. Cicadas (fig. 204) 

 are large, broad insects with membranous wings of considerable 

 size, which may be opaque and brightly coloured. The antennae 

 are very small, and the head not only bears large lateral eyes, 

 but also three simple eyes or ocelli placed in front and often gem- 



