BUGS. . 205 



but in contrast with all of these are the thread-bugs, Emesidae and Berytina, whose 

 bodies and members are as slender and delicate as the extremely attenuated crane-flies 

 of the Diptera. Some are compressed and have the thorax raised high above the body 

 in the form of a currier's knife, or like a Templar's hat. Others imitate beech nuts, 

 buds of trees, bits of dried leaves, scales of dead bark, and even the excrement of 

 caterpillars. 



This order is also rich in sti-uctural elements which servo to associate assemblages 

 of genera in minor subdivisions easily recognizable. But it is difficult to arrange them 

 all in one series, since there is often an addition of one or more elements binding them 

 to small groups at a distance, and forming exceptions to the great balance of their 

 affinities. The structure and position of the legs also vary with the mode of life of a 

 species. Some are fitted for leaping, others for running, and still others fpr grasping 

 tightly the objects upon which they rest. 



Those which crcejJ about in search of living prey are often furnished with curved 

 or hooked fore-legs, suitable for seizing and holding creatures, when in motion, such 

 as caterpillars and other larvas. The anterior femora of many kinds which move about 

 the branches and leaves of trees are set with numerous sharp thorns, sometimes in 

 opposable rows, with which they transfix and hold their victims. 



While the greater number derive their food from either the sap of vegetables or 

 the blood of fishes, animals, and man, there are others which are satisfied with the 

 strong fluid that accumulates beneath damp, decaying bark of trees, or still others 

 which enjoy the juices of fungi or ferns. Among some of the highly developed forms, 

 such as Podisus, Stiretrus, and Mhaphigaster, there are species which live upon the 

 juices of both insects and plants. 



The Hemiptera are either aerial, terrestrial, riparian, or aquatic. Some pass their 

 lives in the upper parts of trees, others chiefly on the lower limbs ; still others prefer 

 the protection of roots, stones, or rubbish on the ground ; a large number of species 

 select a home beneath the surface of the earth, often in the holes of ants or other 

 insects ; a conspicuous assemblage of dull-colored forms occurs only in the crevices or 

 under the bark of trees and shrubs ; while a host of others skim over the surface of 

 placid waters, and a few are found remote from land upon the rarely disturbed waves 

 of the tropical and sub-tropical oceans. 



Their metamorphosis is incomplete, excepting only the males of the Coccidae and a 

 few forms closely related to them. After leaving the egg they generally change the 

 outer skin four times, at intervals of a few days each, to become adults. Growth is 

 thereby permitted, the wing-pads and body become one size larger, and there is only a 

 slight difference to be noticed between the young and the perfect insect. Nothing 

 like a caterpillar stage appears in the newly-hatched creature, and there is no such 

 differentiation as marks the larva, pupa, and imago of Coleoi^tera and the higher 

 orders. The next stage to the adult is commonly called pupa, or nymph, but not 

 because it is in any true sense equivalent to the puj)a of other insects. 



The head is either somewhat flat above and extended forwards nearly in the plane 

 of the thorax, with the eyes seated in or next the base ; or it is spindle-shaped, long 

 conical, or cylindrical, freely movable, with the eyes placed considerably in advance of 

 the base. In most riparian forms the eyes stand out jjrominently from the corners of 

 the broad forehead. The aquatic species have the eyes either deep-seated in the basal 

 angles, or projecting like beads on the sides of the vertepc. In the Corisse the head 

 overlaps the front of the thorax like a cap, and is there attached by a slender neck, as 



