Incoming correspondence of Stephen A. Forbes, Curator of the Natural History Museum (1871-77) and Directory of the State Laboratory of Natural History (1877-1909), concerning identification and classification of entomological specimens, collection and receipt of specimens, making casts and taxidermy, trading and appraising collections, food of birds an fishes, the Illinois Natural History Society, the Natural History museum and library collections, moving the museum to Springfield and the laboratory to Urbana from Normal, state legislation and appropriations affecting natural history, school requests for specimens for cabinets, speeches, exhibits at fairs and expositions, professional meetings, publications and reference books, personnel, field operations and control of insect pests, especially chinch bugs (ca. 1895), and San Jose scale (ca. 1908), microscopes, supplies and equipment and related topics. Forbes' correspondence as State Entomologist was filed separately after 1899. See Record Series 43/4/1.
Correspondents include William Ashmead, W. Beal, Peter Baumgrass, Alembert Brayton, Thomas Brewer, John Caton, J. Henry Comstock, Albert Cook, Nathan Davis, Charles Dodge, Samuel Etter, William Farlow, Charles Fernald, T. Wilson Flagg, George H. French, Orson Galusha, Harrison and Samuel Garman, Asa Gray, John Jenks, John LeComte, Joseph Leidy, Jean Lescuyer, Marshall McDonald, George Morrow, Edward Nelson, Herbert Osborn, Alpheus Packard, Charles Peck, Theodore Pergande, William Pillsbury, Robert Ridgway, Sidney Smith, Goodwin Swezey, Don C. Taft, William Trelease, Addison Verrill, George Vasey, Burt Wilder, and Amos Worthen.