The study of the geographical distribution of insects is a subject which has received attention from many entomologists, yet one which is still in an infant stage of development. Knowledge of the distribution of higher verte brates has progressed to the point where it is fairly well understood, but this is by no means true for insects. Not only are very many insects yet to be discovered or named, but the complete distribution is known for very few. Also, rather little is known of the evolutionary history of insects and there is much contradiction among conclusions relating to the history of insect distribution. It is important enough to know the ranges of the species that occur in an area, in searching for biological control agents, in evaluating pest potentials, crop selection and danger from diseases of plants, animals and man; but zoo geography is much more, however, than the mere determination of the ranges of species or groups. It is, furthermore, a field of interrelation of eco logy* physiology, Systematics, phylogeny, paleontology, geography and geology. It is not a static subject but dynamically relates the tolerances of individuals and populations to their origin, evolution, and dispersal in terms of changing climates, vegetation and topography. The study of insect distribution has progressed to very different degrees in different parts of the world, and for different groups of insects, more or less in proportion to the extent of entomological research. In Europe, where the species and their respective ranges are well known in most groups, very thorough studies have been possible. In some cases it has apparently been possible to work out in detail not only present but past distribution. In other continents where species are still being described and their ranges determined, much pioneering work remains to be done. In few groups of insects has it been possible to determine the course of development and spread of the world fauna, but in recent years a few excellent attempts have been made (168, 121). Though the extremes of geographical range of a species may be easily out lined on a map, it must be remembered that the actual occurrence of a species in most cases involves not only discontinuous macrogeographic dis tribution, but also limitation to a specialized niche within the areal range. Distribution maps should show occurrence by dots, and be supplemented by indication of niche and general habitat or zone, in addition to recording of place-names. More emphasis is now being given to the importance of ecology in zoogeography. The application of insect zoogeography to phylogeny and Systematics is 1 The survey of the literature pertaining to this review was completed in June, 1957. The author has not seen proofs.