<title>Abstract</title> This chapter presents a study attempting to document the most significant arthropod invasions in mainland South America, with particular emphasis on scales (e.g., Coccidae, Diaspididae and Pseudococcidae). A regional species inventory was developed, based upon (gray) literature revision, and employed niche modelling to visualize the geographical distribution of (potentially) some of the most worrisome species. A broad literature revision was carried out to screen invasive species records in mainland South America. Global (e.g., ISI Web of Knowledge, CAB Abstracts) and regional scientific literature databases (e.g., Scielo) were consulted and queries were formulated for invasive or exotic arthropods. For invasive scales, expert knowledge, e.g., TK, DRM or ALP and specialized databases such as ScaleNet were consulted. Focusing monitoring activities on potential ports of entry could be an effective and relatively low-cost option for early detection of invasive species that enter through cargo or passenger transport.