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 
w y ater-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 alj 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 narrowdy 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” 
(iFig. 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.) 
