Collection strengths include Heteroptera, Homoptera, Coleoptera, Lepidoptera, and Diptera. Areas of specialization include mites associated with insects and marine habitats, sphecoid wasps and bees of the world, leaf hoppers and plant bugs of North America, and aquatic insects, litter arthropods, butterflies, moths, and beetles of the Pacific Northwest. Specimens of historic importance include the Hopkins collection of western forest insects, voucher material of the H.J. Andrews LTER, and the Hatch beetle collection. The collection is primarily for use by faculty in their classes. Selections from the collection are exhibited occasionally in the Fairbanks Gallery.
Emphasis is on collections from western North America.
The herbarium is the repository for the Morton E. Peck Herbarium of Willamette University, a research collection of Oregon flora consisting of more than 30,000 sheets, and the former University of Oregon herbarium. These collections include the H. C. Gilbert Myxomycete Collection and the Forest Service Pathology Herbarium. In addition, there are about 260,000 uncataloxged specimens available for study. The collection emphasizes fishes of the Pacific Northwest, but specimens from many parts of the world are held. A small frozen tissue collection has been started.