This collection includes letters, manuscript and typescript drafts of his publications. They relate to his works Fighting the Insects: the Story of an Entomologist (1933); and with Harrison D. Dyar and Frederick Knab, A Monograph of the Culicidae of North and Central America. The latter is one volume of the larger three-volume published work The Mosquitoes of North and Central America and the West Indies (1912).

The approximately 3,700 color and black and white drawings were collected and drawn by John Lawrence LeConte, with two in the first volume are by Titian R. Peale, but most are likely by John Abbot. The previous description noted that there are some drawings by John Abbot, and that most were likely by John Lawrence Le Conte. However, John V. Calhoun has shown extensive evidence that most of the drawings are by John Abbot (John Abbot's "Lost" Drawings for John E. LeConte in the American Philosophical Society Library, Philadelphia. Journal of the Lepidopterists' Society 60(4), 2006, 211-217). The contents of the collection: 1. Coleoptera. 654 figures. 2. Diptera, Hemiptera, and Lepidoptera. 564 figures. 3. Coleoptera. 698 figures. 4. Coleoptera and Hymenoptera. 228 figures. 5. Coleoptera. 657 figures. 6. Hymenoptera and Diptera. 234 figures 7. Diptera. 304 figures. 8. Hemiptera, Araneina, Myripoda. 356 figures

These papers include letters on natural history, metals and mineralogy, botany, insects, the geological survey of New York, and analyses of distilled liquors in the cause of temperance.

This collection contains mostly entomological material, with much information on the description and identification of particular insects, entomological collections, and the study of entomology in Europe and the United States. In addition, there are materials on medicine and hospitals during the American Civil War, on the Corps of Topographical Engineers, the United States Army, on natural history in the United States, and on the LeConte's family. Some letters are written to President Rutherford B. Hayes and concern the Commissionership of Agriculture, for which LeConte was considered, but not appointed. Letters of John Eatton LeConte and Joseph LeConte are included.