The Neuroptera (or Planipennia), one of the most archaic groups of endopterygote Neoptera, is a small order, with a little more than 5000 described species.
The interactive LUCID key available on this website (see the 'Identify Families' link) was written by Shaun Winterton of the QDPI and the University of Queensland.
Adults range from very small insects with a wing-span of about 5 mm to very large forms with wing-span exceeding 150 mm. Although many are cryptically coloured, others are brightly coloured and patterned, and many are clothed with long, dense hairs.
Some taxa are very swift fliers (Ascalaphidae, in particular) but most fly rather slowly and irregularly and in these the wing-coupling mechanism, if present, appears inefficient.
Sexual dimorphism is generally slight, but is especially marked in some Ascalaphidae in which males have a dorsal abdominal process. There are differences in wing shape between the sexes of some Hemerobiidae and Chrysopidae and the berothid
Most lacewings are recognisable by their having the main veins branched (or 'twigged') at the end, and by the way they hold their wings in a steep `roof' while at rest.
Most Neuropteran larvae are predatory on other insects or arthropods, and catch their prey using both 'sit-and-wait' and active means. Many Chrysopidae and Hemerobiidae are cursorial on foliage, and the larvae of Myrmeleontidae (the 'ant-lions') are well-known for the conical pitfall traps they built in sand, to catch ants and other insects wandering past. The Mantispidae are unusual in that larvae are parasitic, usually within the egg sacs of spiders, and larval Sisyridae (the 'sponge-flies') feed aquatically upon freshwater sponges. A very few Neuroptera feed on decaying plant material (New 1991).
The largest families are Chrysopidae and Myrmeleontidae, each with around 2000 described species. The immature stages of Neuroptera were discussed by Withycombe (1925) and a synopsis of larval forms is given by Gepp (1984). Recent revisions have considerably improved knowledge of the Australian fauna (e.g. Aspöck and Aspöck 1984, 1985, 1986; Lambkin 1986a, b; Mansell 1983; New 1980-1988; Riek 1974b, 1976), and the biology of the order is reviewed by New (1986d). A more extensive, general account of the order is given by New (1989b).
Note: The two bottom families in the key are of the Order Megaloptera, and have been included here as they are easily mistaken for members of the Order Neuroptera.
Endopterygote, mandibulate Neoptera; antennae multisegmented, filiform, moniliform or variously thickened, usually conspicuous; compound eyes always present; ocelli usually absent; generally two pairs of large, equal or subequal membranous wings, often with numerous cross-veins; main veins usually with `end-twiggings'; trichosors often present.
Most larval Neuroptera are easily distinguished by the sickle- or needle-shaped sucking mouthparts formed by the elongate mandibles and maxillary lacinae, and the complete absence of maxillary palps. Some glossatan Lepidoptera also lack maxillary palps, although the presence of chewing mouthparts, and a median labial spinneret should serve to distinguish them from lacewing larvae.
Neuroptera is represented in all major zoogeographical regions, usually being more abundant in the tropics than in temperate areas. Neuroptera occur throughout Australia. Globally, some of the families are geographically limited, and many are small, some having only a few tens of species.
Australian Neuroptera include many of the more archaic groups and some higher taxa scarcely found elsewhere in the world. Although some genera of many families are globally widespread, endemism at both generic and specific levels is very high and well over 90% of Australian species are not known from outside the country. The northern fauna sometimes has affinities with that of New Guinea, and some elements of the Bassian fauna are related to taxa in South America. Four small families appear to be absent from Australia: Brucheiseridae, with 2 small South American species; Rapismatidae, a primitive group formerly allied with Ithonidae, are montane Oriental; Dilaridae are Holarctic, Neotropical and Afrotropical; and Polystoechotidae occur in both North and South America.
Nymphidae (which are thought to represent the line of development leading to the higher Myrmeleontoidea) occur only in Australia, Lord Howe Island and New Guinea, with an early, unconfirmed record from the Philippines, and Psychopsidae are otherwise known from southern Africa and the Oriental Region. Ithonidae are almost entirely Australian. Myrmeleontidae: Stilbopteryginae (earlier considered as part of a distinct family, Stilbopterygidae) occur only in Australia. Two of the primitive genera of Chrysopidae: Nothochrysinae occur in south-eastern Australia, and the Osmylidae are diverse, with some subfamilies shared only with South America and New Zealand.
As a result of recent revisionary studies, adults of the Australian Neuroptera are now tolerably well known, although undoubtedly many further species await description. Many families are widely distributed in Australia but, in general, Myrmeleontidae and Ascalaphidae are most abundant in the drier regions. The Myrmeleontidae: Dendroleontini are a predominantly Australian radiation with relatively few species elsewhere. Some other families (Psychopsidae, Nymphidae, Coniopterygidae) are most diverse in the east and south-east and Osmylidae are particularly characteristic of subalpine areas with a few species being found above the treeline. The fauna of Tasmania is relatively impoverished but at least 9 families are present with species representing both widespread taxa and the eastern Bassian fauna. The only possible Tasmanian endemics are some Osmylidae.