164 Bugs, Cicadas, Aphids, and Scale-insects 



nificant-looking scale-insects make the orchardist and vine-grower similar 

 believers in supernatural moral correction by means of insect-scourges, 

 and the piercing and sucking lice and bugs in the English meaning make 

 personal and domestic cleanliness a virtue that brings its own immediate 

 reward. 



Other not unfamiliar representatives of this order are the loud-singing 

 cicadas with their extraordinarily protracted adolescence, the thin-legged 

 water- striders and skaters of the surface of pond and quiet trout-pool, the 

 oar-legged water-boatmen and back-swimmers of the depths of the same 

 pools, the ill-smelling squash-bugs, calico-backs, and stink-bugs of the 

 kitchen-gardens, the big, flat-bodied, electric-light or giant water-bugs that 



whirl like bats around the outdoor arc-lights, 

 and the assassin- and "kissing "-bugs of one- 

 time newspaper interest. In structure all the 

 Hemiptera agree in having the mouth-parts 

 formed into a piercing and sucking beak (Fig. 

 234) capable of taking only liquid food. As 

 that food is nearly always the blood of living 

 animals or the sap of living plants, the nearly 

 uniformly injurious or distressing character of 

 the food-habits of all the members of the 

 order is apparent. This beak is composed 

 of the elongate, tubular under-lip (labium) 

 acting as sheath for the four slender, needle- 

 like piercing stylets (modified mandibles and 

 maxillae). The labium is not a perfect tube, 

 for it is narrowly open all along its dorso- 

 medial line, but the edges of this slit can be 

 brought closely together and the slit also 

 covered internally by the stylets, so that an 

 effective tubular sucking proboscis is formed 

 (Fig. 14). The name Hemiptera is derived from 

 the character of the fore wings shown by most, 

 though by no means all, of the members of the 



order; this is the thickening of the basal half of the otherwise thin, 

 membranous wing, so that each fore wing is made up of two about equal 

 parts of obviously different texture and appearance; hence " half- winged " 

 (Fig. 268). All Hemiptera (excepting the male scale-insects) have an incom- 

 plete metamorphosis, the young at birth resembling the parents in most essen- 

 tial characteristics except size and the presence of wings. By steady growth, 

 with repeated moultings and the gradual development of external wing- 

 pads, the adult form is reached, without any of the marked changes apparent 



FIG. 234. Diagram of section 

 through head and basal part 

 of beak of a sucking-bug. 

 ph., pharynx; m., muscles 

 from pharynx to dorsal wall 

 of head; v., valve; s., stop- 

 per; m., muscle of stopper; 

 s.d., salivary duct; lr., la- 

 brum ; b., one of the stylets 

 of beak. To pump fluid up 

 through the beak, the mus- 

 cle attached to the stopper 

 contracts, thus expanding the 

 cavity closed by the valve. 

 (After Leon.) 



