This guide aims to facilitate the identification of grasshoppers, locusts, bushcrickets and crickets (Orthoptera) that are known or suspected to act as pests in the Indo-Malayan region, and to summarize published information on their distribution, biology, ecology, food plants and economic importance. An illustrated key is provided for the identification of the species and species groups treated in this guide. As far as possible, the key uses characters that are discernable without a magnifying glass. Inevitably, in some cases characters had to be used that require the use of a hand-lens or stereo-microscope. For some species groups a key to the level of species is lacking since identification would require the examination of male and female genitalia. In the systematic section, families are characterized morphologically, and general remarks on their distribution, species numbers worldwide, and biology are provided. Information for each species (or species group) includes, as far as known, notes on nomenclature, morphology, distribution, life cycle, ecology and behaviour, food plants and economic importance.