I am indebted to Mr. Maiden for the identification of the native food plants of many insects. I am also greatly indebted to Mr. W. S. Campbell for permission to use the drawings of Messrs. Grose, Burton, and Chambers, which have previously appeared in the pages of _The Agricultural Gazette of N.S.W._, and which for beauty and accuracy have rarely been surpassed. To Mr. Burton and Mr. Gurney my thanks are also due for their care in arranging and photographing other specimens. To the other friends who have kindly aided me in this undertaking in any way I beg here to offer my best thanks. AUSTRALIAN INSECTS. CLASSIFICATION. In considering the classification of our insects, I have on the whole followed that adopted by Sharp in his “Insects” (vol. v., vi., 1895, 1899), Cambridge Natural History, but at the same time have considered it advisable, in a work of this kind, to leave out whenever possible the definition of the smaller sub-divisions. I have also made one important alteration in his scheme of classification by placing the Termitidae after the Blattidae, following on with the Embiidae and Psocidae, as I consider that these are nearer primitive Orthoptera than Neuroptera in their wing structure; we thus do away with Pseudo-Neuroptera that has always appeared to be an unnecessary division; and we should have the courage of our convictions and place them on one side or the other. In zoological classification, the sub-kingdom Arthopoda, comprising creatures whose bodies are composed of rings or segments, and jointed legs, contains four large groups: (1) Arachnidae, spiders, mites, ticks, and scorpions; (2) Crustacea, crabs, shrimps, wood lice, &c.; (3) Myriapoda, centipedes, millepedes, &c.; (4) Insecta, insects; and a fifth group, Onychophora, containing the _Peripatus_, is now included. Though these creatures are broadly related, insects are readily distinguished from the members of the preceding groups. The word Entomology is derived from two Greek words, _Entomos_, an insect; and _Logos_, a discourse. Insects are arranged by entomologists in Orders, Families, Genera, and Species. The first clearly-defined classification was published by Linnaeus in his “Systema Naturae,” 1758, where he divided them up into seven great orders; namely, Coleoptera, Hemiptera, Lepidoptera, Neuroptera, Hymenoptera, Diptera, and Aptera, distinguished by the number and structure of the wings. Later on (1778) Fabricius founded another classification, based on the structure of the organs of the mouth, but this artificial arrangement soon became obsolete.