204 NATURAL HISTORY OF ARTHROPODS. 



OEDER VI. HEMIPTERA. 



This great group of insects, many of which are called Bugs, embraces a large 

 assemblage of very diverse forms, apparently not closely related to each other, and hav- 

 ing widely different modes of life. Their true composition is often disguised by 

 modifications which have reference to some peculiarity of habit, or to stress of locality ; 



but when these features are stripped off, there remains a basis 

 of essential structure to connect all in one common group. 



Two principal kinds of structure pervade the series and 

 serve to separate it from all other orders of insects. The first 

 of these appears in the mouth-organ, concurrent with modifica- 

 tions of the head and breast (sternum). This instrument, the 

 rostrum, consists of a horny, jointed, tapering tube, the labium, 

 arising from the front of the head beneath, and enclosing four 

 stiff bristles, the mandibles and maxillae, adapted for piercing 

 the tissues of plants or the skin of animals. By the aid of 

 contractile muscles it imbibes the fluid nourishment suited to 

 sustain the life of the insect. This rostrum is sometimes very 

 long and slender, especially when the creature has to probe 

 deep into the plant upon which it lives ; or it is short and thick 



FIG. 286. Under surface of 



r,:;nia, showing the ros- when the species finds food near the surface. The modifica- 



trum. 



tions of the sternum usually coincide with the form and use 

 of the rostrum, and constitute a support for the movements of the head and its 



organs. 



The second kind of structure appears in the organs of flight, the hemelytra or fore- 

 wings and the hinder parts or wings proper. There are two principal types of the 

 former which will be more fully noticed under the divisions Homoptera and Heter- 

 optera. In general these are thick and leathery or crustaceous at base, and mem- 

 branous at tip. In certain degraded forms, such as the bed-bug and lice, no wings are 

 ever developed ; while in the aquatic genera Hygrotrechus and Limnotrechus, there 

 are individuals entirely unwinged, half-winged, or with fully developed hemelytra and 



wings. 



The name of this order is derived from hemi, half, and pteron, a wing, having 

 reference to the thick base and abruptly thin tip in the more commonly described 

 division, the Heteroptera. 



Scarcely any other great group of insects displays such a wide range of diversity 

 as we see in this. Almost every pattern of form or style of marking to be found in 

 the other orders occurs here, and that too with features of external structure not met 

 with elsewhere. A few of these may be seen in the plate which heads this article. 

 Besides the more prominent types of this order, which in North America is represented 

 by the leaf-hoppers, tree-hoppers, cicadas, giant water-bugs, water-boatmen, wheel- 

 bugs, chinch-bugs, squash-bugs, and plant-bugs, there is an almost countless host of 

 small forms belonging to the scale-lice, plant-lice, and field bugs. 



Among the terrestrial and more beetle-like forms, with broad oval and convex 

 bodies, we notice the Pachycorids, Corimelrenas, Stiretrids, Cydnids, and Pentatomids ; 

 those with elliptical bodies, flat above, belong to such groups as the Lygasidae and 

 Coreidse, while exceedingly depressed forms are present in the Aradidoe and Tingitidje ; 



