This collection contains the papers of William Logan Threlkeld, professor of zoology and biology at Virginia Polytechnic Institute from 1929 to 1958. The collection contains biographical materials, personal and professional correspondence, research files, and printed materials.

Though there is much overlap between the personal and professional correspondence, letters of a predominantly personal nature from family members, aquaintances, former teachers, and former students, are found at the beginning of the collection. Also from Threlkeld's personal life are a collection of materials relating to various awards and memberships, as well as his military service. A folder of biographical materials contains a booklet about the Threlkeld School, operated by Threlkeld's father; a 1929 biology exam book from University of Virginia; a bibliography of Threlkeld's works; and various biographical sketches. Also relating to Threlkeld's personal life is material on the honor society of Sigma Xi. The collection also contains numerous opinion pieces written by Threlkeld, a number of them in the form of letters written to newspapers and political figures and largely focused on communism. Accompanying these pieces is a small collection of printed materials reflecting Threlkeld's political views.

From Threlkeld's professional career, the collection contains several subject files relating to both his scientific research and his work for the Virginia Cooperative Extension Service. Included are project folders on parasites in cattle, sheep, and swine, with a particular emphasis on the relationship between cobalt deficiency and the presence of parasites in sheep. The correspondents include not only other researchers but various Virginia farmers with whom Threlkeld worked. These folders contain correspondence, project reports, and notes. The collection also contains a folder of general research correspondence, as well as professional correspondence not directly tied to any specific research and administrative correspondence relating to Threlkeld's career, students, and retirement. Also included is a collection of Threlkeld's publications as well as files relating to his book, Some Nematode Parasites of Domestic Animals. These folders contain reprint requests, book orders, and business records and correspondence relating to the book's publication.