The Lepidoptera collection and staff are located on the fifth floor, East Wing, NMNH. The library resources relating to Lepidoptera consist of 2,000 volumes and 370 linear feet of reprints in file cabinets. The Lepidoptera collection occupies 27,483 drawers and is estimated to contain more than 4,000,000 specimens. These include over 25,000 primary types. The larval collection is one of the largest in the world, occupying 1,132 storage racks (specimens in alcohol) and 132 drawers (inflated larvae), estimated to contain a total of about 123,000 specimens. Included also are 131 slide cabinets containing about 100,000 microscope slides, mainly of moth genitalia. The present SEL research staff working on Lepidoptera includes David N. Adamski, John W. Brown (Location Leader, NMNH), Michael G. Pogue, and M. Alma Solis. The Smithsonian staff includes John M. Burns, Don R. Davis, Scott E. Miller, and Robert K. Robbins.

The first specialist to work on Lepidoptera, was employed by the Smithsonian Institution in 1885. He was followed by a series of USDA entomologists, including F. Benjamin, A. Busck, H. W. Capps, J. F. G. Clarke (subsequently employed by the Smithsonian), H. G. Dyar, W. D. Field (subsequently employed by the Smithsonian), J. G. Franclemont, C. Heinrich, W. Schaus, E. L. Todd, and D. M. Weisman.

The collection is strongest in Nearctic material, rich in Neotropical and Palearctic species, and progressively less rich in Oceanic, Oriental, Australian, and African material.Especially well-represented exotic groups include Lycaenidae and Pieridae; European and Japanese microlepidoptera; and Taiwanese, Philippine, and Szechwan moths in general.

Major acquisitions that have been incorporated into the museum holdings over the years are the collections of A. Alfieri (Egypt); C. F. Baker (Philippines, Malaysia); J. H. Baker (Oregon moths, esp. Geometridae); W. Barnes (North America, incl. types of Barnes & McDunnough, Guenee, Boisduval, Kearfott, Hill, Taylor, and the Merrick coll.); E. H. Blackmore (British Columbia); A. Blanchard (Texas); H. E. Box (sugar-cane feeding Pyralidae); The Brighton Museum (British microlepidptera); The Brooklyn Museum (North America); A. E. Brower (North America, esp. Maine); J. F. G. Clarke (Pacific Northwest); P. Dognin (South America); H. G. Dyar (North and South America); G. P. Engelhardt (Sesiidae); D. C. Ferguson (North America, esp. Atlantic Provinces); C. H. Fernald (North American, incl. some type material of Fernald, Fitch, Fish, Walsingham, Hulst, Packard, and Grote); W. D. Field (Japanese and European butterflies); J. G. Franclemont North American Saturniidae, Sphingidae, and microlepidoptera); E. L. Graef (North America); J. A. Grossbeck (North America); R. W. Hodges (North American microlepidoptera); S. Issiki (Japanese microlepidoptera); E. Jackh (Texas and Palearctic microlepidoptera); A. Kawabe (Japanese and Taiwanese microlepidoptera); W. S. McAlpine (Riodinidae); B. Neumoegen (North America); A. Philpott (New Zealand microlepidoptera); W. Schaus (Tropical America); and E. A. Smyth (American and exotic Lepidoptera). The collection also contains many of the types of J. B. Smith, and types of many others who have studied NMNH material, including Diakonoff, Munroe, Rindge, Shaffer, and Warren.

The largest acquisitions were the Barnes collection (nearly a half million specimens), purchased by the USDA in 1931, the C.F. Baker collection (300,000 specimens) donated in 1928, and the Schaus collection (200,000 specimens) donated in 1901 and following years. The Barnes and Schaus material accounted for most of the North American and Tropical American Lepidoptera holdings respectively for over 40 years. However, with renewed interest in field work and curation, current USDA and Smithsonian lepidopterists have greatly improved the collection, adding about as many specimens from their own collecting as did all of their staff predecessors combined.