Key to Families of Australian Aquatic Hemiptera (True-bugs)
The Hemiptera (true bugs) are a widespread and speciose order of insects. The large terrestrial element includes leafhoppers, cicadas, aphids, scale insects, and a variety of herbacious and predatory bugs. The smaller aquatic element includes water striders, water boatmen, backswimmers, water scorpions and a range of lesser-known forms.
Some families in this key are wholly aquatic. Others are terrestrial with an aquatic or semi-aquatic component. Included here are all families with at least some more-or-less aquatic species in Australia. The one ‘surprise’ in the key might be Aphididae, included not because aphids are small and fall into aquatic samples (although they do) but because a very few truly aquatic species feed underwater on plant stems. The remaining families fall into three ecological guilds: the water surface specialists of infraorder Gerromorpha (5 families: Mesoveliidae, Hebridae, Hydrometridae, Veliidae, Gerridae), the shore-line and semiaquatic Leptopodomorpha and Dipsocoromorpha (4 families: Leptopodidae and Saldidae, Ceratocombidae and Dipsocoridae), and fully aquatic bugs of infraorder Nepomorpha (8 families: 5 of water bugs (Nepidae, Belostomatidae, Ochteridae, Gelastocoridae, Naucoridae), 1 the water boatmen (Corixidae), and 2 the backswimmers (Notonectidae, Pleidae)).
The most obvious common feature of all Hemiptera is their suctorial mouthparts, which consist of hinged stylets (mandibles and maxillae) resting in an anteriorly grooved rostate labium. Almost all species are distinctively bug-like to look at although a few corixids, etc., with a rounded look and short mouthparts might at first glance be mistaken for beetles. Identification to family level can be based on body proportions, shape of head and prothorax, leg configuration and other readily-visible external features.
Hemipteran development is direct, the juveniles looking typically rather like the adults but with un-formed or partly formed wings. Many adults too are apterous, or nearly so. Because all life stages are similar, adults and juveniles can be covered to family level in a single key. However, the earliest instars of some species might not be fully identifiable to family, and this should be borne in mind when using this key.
Key Author(s): CSIRO Entomology Key Version: 1.1
