The SDSU Terrestrial Arthropods Collection includes an estimated 50,000 specimens of pinned insects, a slide-mount collection, and many terrestrial arthropods (e.g., insects, arachnids, myriapods) preserved in ethanol. Most of these specimens were collected in southern California and adjacent regions (e.g., Arizona, Baja California Mexico). The collection holdings in Arachnida, Orthoptera, Lepidoptera, and Coleoptera are particularly strong. The collection is an important resource for both the teaching and research missions of the Department of Biology at SDSU, with a synoptic collection of local insects kept specifically for this purpose.