INSECTA. 257 
ORDER VII.— Hemiptera. 
In this order there is great variety in the wings, which 
are often absent, but the mouth parts are typically 
“sucking,” the labium forming a long sucking “ rostrum,” 
and the metamorphosis is incomplete. The Hemzptera 
are mostly either aquatic insects or dwell on plants and 
Fig. 180.—THE Common Louse (Pedicudus),. 
«, Natural size; 4, magnified; c, a leg ; d, hair with ‘‘nits” or eggs; e, ditto 
magnified. A degenerate Hemipterous insect. oa 
Fig. 181.—THE Rose ApHIs. 
suck their juices. Of the aquatic types the “ water- 
scorpion” has the first pair of legs modified into kind of. 
maxillipedes; the water-boatman swims at the surface on its 
back, the hind legs imitating a pair of oars. Of the 
terrestrial type the green aphis is peculiar in reproducing 
parthenogenetically during the summer, and in secreting a 
juice of which ants are very fond. 
OrpbER VIII.—Apeera. 
A few small insects comprise this order, their mouth 
parts are biting, they have no wings and no metamorphosis. 
M. 18 
