Today's distributions of faunal groups reflect historic events—geological and evolutionary, as well as dispersals, extinctionsand chance events. The extent to which each of these contributed to the hydroptilid faunas of mainland Australia,Tasmania, New Guinea, New Zealand, New Caledonia, Fiji and Vanuatu is explored by comparison of the faunal composition,geology and geography of Australia and these SW Pacific islands. Corroborative evidence is sought from othergroups, flora as well as fauna.