_Gymnocerata._--This tribe includes some eighteen families of terrestrial, arboreal and marsh-haunting bugs, as well as those aquatic Heteroptera that live on the surface-film of water. The feelers are elongate and conspicuous. The _Pentatomidae_ (shield-bugs), some of which are metallic or otherwise brightly coloured, are easily recognized by the great development of the scutellum, which reaches at least half-way back towards the tip of the abdomen, and in some genera covers the whole of the hind body, and also the wings when these are closed. The _Coreidae_ have a smaller scutellum, and the feelers are inserted high on the head, while in the _Lygaeidae_ they are inserted lower down. These three families have the foot with three segments. In the curious little _Tingidae_, whose integuments exhibit a pattern of network-like ridges, the feet are two-segmented and the scutellum is hidden by the pronotum. The _Aradidae_ have two segmented feet, and a large visible scutellum. The _Hydrometridae_ are a large family including the pond-skaters and other dwellers on the surface-film of fresh water, as well as the remarkable oceanic genus _Halobates_ already referred to. The _Reduviidae_ are a family of predaceous bugs that attack other insects and suck their juices; the beak is short, and carried under the head in a hook-like curve, not--as in the preceding families--lying close against the breast. The _Cimicidae_ have the feet three-segmented and the forewings greatly reduced; most of the species are parasites on birds and bats, but one--_Cimex lectidarius_ (figs. 3, 8)--is the well-known "bed-bug" which abounds in unclean dwellings and sucks human blood (see BUG). The _Anthocoridae_ are nearly related to the _Cimicidae_, but the wings are usually well developed and the forewing possesses cuneus and embolium as well as corium and clavus. The _Capsidae_ are a large family of rather soft-skinned bugs mostly elongate in form with the two basal segments of the feelers stouter than the two terminal. The forewing in this family has a cuneus (fig. 9 cu), but not an embolium. These insects are often found in large numbers on plants whose juices they suck.
[Illustration: After M. V. Slingerland, _Cornell Univ. Ent. Bull._ 58.