The _Heteroptera_ constitute the first sub-order of the _Hemiptera_.
They include the True Bugs, an extensive group of very varied
structure and habits. The greater part of the terrestrial species feed
on plants, though some feed on the blood of animals, while the aquatic
species are principally carnivorous in their habits. This sub-order is
divided into two tribes.
[Illustration: Fig. 80.--Graphosoma Lineatum (Mag.)]