Biological inventories often miss parasites, a critical component of biodiversity, and even well-studied host species generally have a paucity of parasite records. Efforts to document the host diversity and distribution of parasites can use newly collected specimens as well as museum specimens. We focus on a group of widespread, well-documented hosts, western North American chipmunks (Rodentia: genus Tamias). Field-collected and museum specimens of chipmunks from across western North America were examined externally for sucking lice (Anoplura), and gastrointestinal tracts were examined for pinworms (Oxyuriodea). We documented new hosts and expanded the geographic distribution for four parasite taxa under investigation: Hoplopleura arboricola, Neohaematopinus pacificus, Heteroxynema cucullatum, and Rauschtineria eutamii. This effort demonstrates the utility of museum collections as well as the pressing need for continued field collection to characterize global biodiversity.