Spinosad, Saccharopolyspora spinosa, is widely used as a stored product protectant. However, its efficacy against the hide beetle Dermestes maculatus DeGeer (Coleoptera: Dermestidae), a major pest of dried animal-based materials, remains underexplored. In this study, we evaluated the contact and oral toxicities of spinosad across a range of concentrations applied directly to animal-derived substrates. Larval and adult mortality, along with probit parameters, were determined to assess susceptibility. Spinosad produced significant mortality in both life stages, with larvae exhibiting higher susceptibility under contact exposure, whereas adults showed increased susceptibility under feeding exposure. These patterns are consistent with prior reports of spinosad’s dual-action toxicity against stored-product pests. The larval contact and adult feeding exposures to spinosad were positively associated with higher doses, while adult contact and larval food exposures aligned with lower doses. The larval contact and adult ingestion routes drive the strongest toxic responses, whereas adult contact and larval feeding elicit weaker effects under the same doses. Overall, our results highlight spinosad as a promising tool for integrated pest management of hide beetles in animal-based storage systems.