This text is designed to facilitate identification of South American insects likely to be encountered in, on, or near water, on wetlands, and in unusual aquatic habitats, such as bromelias, pitcher plants, and mosses. In the case of some taxa encompassing both aquatic and terrestrial species, it is expanded to permit identification of all species, regardless of habitat. This work begins with a short general introduction. The scope for the first volume is the Collembola. It includes all species known from South America by the end of the 1990s and permits a state-of-the-art identification to species. In the case of specimens belonging to undescribed species or those not previously reported from South America, it permits identification to genus or family and gives the reader reasonable certainty that his specimen does not belong to the known fauna of the continent. The keys are richly illustrated to permit non-specialists in the group to reliably identify specimens. Taxnomic revisions are intentionally avoided, but doubtful taxa are so-designated in the key.