HEMIPTERA 



351 



corium; this is the embolium (Fig. 400, e). In certain other cases, as 

 the Miridas for example, a triangular portion of the terminal part of 



Fig. 399. — Diagram of a front wing of 

 a bug: cl, clavus; co, corium; m, 

 membrane. 



Fig. 400. — Diagram of a front wing of 

 an anthocorid: e, embolium. 



the corium is separated as a distinct piece; this is the cuneus (Fig. 

 401, cu). 



The wings of the Hemiptera exhibit remarkable departures from 

 the primitive type of wing-venation. So great are these that, at 

 first, one sees very little in com- 

 mon between the wings of a 

 bug and those of insects of any 

 other order. But an examina- 

 tion of the tracheation of the 

 wings of n^Tnphs of bugs shows 

 that these wings are merely 

 modifications of the primitive 

 type of insect wings. This is 

 more obvious in some families 



than in others; it is well shown Fig- 401.— Diagram of a front wing of a 

 in the tracheation of a fore "^"^- ^«' <^^"^"^- 

 wing of a pentatomid nymph 

 (Fig. 402). 



The head in the Hemiptera varies greatly in form in the different 

 families; but the accompanying figures of the head of one of the 

 Belostomatidas, Lethocerus (Figs. 403 and 404), will serve to illustrate 

 the position and form of the parts that are commonly referred to in 

 descriptions of members of this order. 



There are two factors which make difficult the determination of 

 the areas of the surface of the head in these insects that have been 

 recognized and defined in the more generalized insects (see pages 3 7 

 to 40) : first, in some cases the sutures that limit these areas in the 

 more generalized insects are here obsolete; second, the basal part of 

 each mandible and of each maxilla enters into the composition of the 

 wall of the head. 



A similar modification of the head and mouth-parts exists in the 

 Homoptera, and the students of the Hemiptera should study the 

 relations of the mouth-parts to the head-capsule in that order, where 

 they are more easily seen than in the Hemiptera. 



