Key to Families of New Zealand Heteroptera (Adults)

The Hemiptera are distinguished from all other insects by the form of the mouth-parts. which are piercing and sucking and consist of bristle-like maxillary and mandibular stylets held in a longitudinally grooved rostrum derived from the labium, which itself is not piercing or sucking and is apically narrowed and not labellate and in repose is usually bent back and held beneath the head or body; palps absent or vestigial; labrum short, not piercing or sucking. The Heteroptera differ from the Homoptera in the following respects wings, when present, usually overlapping behind; fore-wings, when fully developed, in the form of hemelytra, with the basal region usually coriaceous and the apical region membranous (in the Cryptostemmatidae the corrum and membrane are not or are imperfectly differentiated and in the Henicocephalidae the hemelytra are membrenous throughout); with a sclerotized gular plate, so that frons and clypeus are usually dorsal or anterion and not deflected strongly to face ventrally (exceptions in New Zealand are the Corixidae and Notonectidae. with a certain amount of ventral flexure); base of rostrum usually not touching anterior coxae and never appearing to arise between them; pronotum large. In Gymnocerata brachypterous adults are to be distinguished from nymphs by the absence of dorsal abdominal scent gland openings and the presence of the gland apertures on the venter of the thorax. The nymphs are always without ocelli, but the adults of some (e. g., all Miridae) also lack these structures. Usually the adult has three tarsal segments and the nymph two, but in some groups (e.g., Acanthosomatinae) there are only two in both adults and nymphs. The extent of development of the external genitalia in the nymphs is variable. The adults of all New Zealand Pentatomidae have five antennal segments, the nymphs only four. The hemelytra of brachypterous adults often have a reduced membrane, never present on the wing-pads of nymphs.

In this and subsequent keys, length, unless otherwise stated, is the total straight body length from apex of head to tip of abdomen (or of closed hemelytra when these surpass the abdomen)