As an adult, Joicey began collecting Lepidoptera in 1906 and by 1908 was advertising as far away as Australia for: Fresh-caught Specimens of Butterflies and Large Moths, in papers. Send Samples and state price per hundred. He acquired the
Henley Grose-Smith collection in 1910. Two years later he bought the
Herbert Druce collection. To house his growing collection, he founded the Hill Museum at his Witley home in 1913. and
George Talbot (from 1915), with a staff of assistants. and
New Guinea). W. J. C. Frost, who visited the Islands of
Tenimber, Am, Key,
Misol, Obi and Sula during 1915–1918, donated his collection. Another collector, C. Talbot Bowring, sent many thousands of specimens from Hainan Island between 1918 and 1920. In 1919, the collection was valued at £50,000 (approximately ). It consisted of 1.5 million specimens held in a room containing chests of drawers with "5000 compartments neatly arranged round the room, and in addition 4000 cases, all carefully labelled". It was reported that, Here were butterflies of all sizes, of all colours – all arranged in an effective colour grouping. In one compartment were ... great winged beauties half a foot from wing tip to wing tip. In another were creatures so small that it needed a microscope to discern their beauty. These include the four volumes of
The Bulletin of the Hill Museum, 1921–1932, edited by Joicey and Talbot, and
A Catalogue of the Type Specimens of Lepidoptera Rhopalocera in the Hill Museum, 1932, by
Alfred George Gabriel. During his lifetime, Joicey "presented to the Nation" between 200,000 and 300,000 Lepidoptera specimens including about 75,000 to the Natural History Museum. The latter figure included 15,500 moths and a number of butterflies (1923), his whole collection of over 30,000
Hesperiidae butterflies (1926), 6,000
Lymantriidae moths (1928), and, in 1931, a series of 800
type butterflies being "the most valuable, both scientifically and intrinsically ... received for the past two decades", some thousands of moths including over 600 type and
paratype moths, and 1,500 butterflies including 750 type specimens. In 1932, the collection numbered over 500,000 specimens. Shortly after Joicey's death in 1932 the Hill Museum was closed and the property sold by his mother's
executors. Joicey's obituary in
The Entomologist stated that, The closing of the Hill Museum and the disbanding of its staff are events which will have serious repercussions throughout the ranks of lepidopterists in all parts of the world, and will definitely retard the advance of this science. In a comparatively short space of time Mr Joicey accomplished much for his favourite study. File:BulletinHillMuseum1921HillMuseumExterior.jpg|alt=Sepia photograph of the outside of building with four arched windows|Hill Museum: Exterior File:BulletinHillMuseum1921HillMuseumAnnexe.jpg|alt=Sepia photograph of a long single-story barracks hut in a field|Hill Museum: Annexe File:BulletinHillMuseum1921HillMuseumInterior.jpg|alt=Sepia photograph of a room crowded with display cabinets and work benches|Hill Museum: A part of the interior File:BulletinHillMuseum1921HillMuseumPhotomicrography.jpg|alt=Sepia photograph of man adjusting photographic equipment on a bench|Hill Museum: Photomicrographic Department under Mr. H. J. Campbell File:BulletinHillMuseum1923.jpg|alt=Sepia photograph of six gentlemen standing outside on pathway stairs|Joicey (second from left) and other entomologists at the Hill Museum in 1920 File:BMNH(E)983480 Delias joiceyi Talb. female3 ventral-S.jpg|alt=Photograph of a pinned butterfly with notes below|
Delias joiceyi File:BMNH(E)983400 Delias maudei J.&N. male ventral-S.jpg|alt=Photograph of a pinned butterfly with notes below|
Delias maudei File:BMNH(E)141732 Delias mariae J.&T. AT female ventral-S.jpg|alt=Photograph of a pinned butterfly with notes below|
Delias mariae File:Ornithoptera goliath samson f. joiceyi Noakes & Talbot, 1915.jpg|alt=Photograph of a pinned butterfly with notes below|
Ornithoptera goliath samson f.
joiceyi File:Annalsmagazineof8151915lond 0649.jpg|alt=Book page showing watercolour plate of butterfly specimens|
Ornithoptera joyceyi (male), two
Delias File:Annalsmagazineof8151915lond 0651.jpg|alt=Book page showing watercolour plate of a butterfly specimen|
Ornithoptera joiceyi (female) File:DeudorixMaudeiMFJoiceyTalbot1916.JPG|alt=Book page showing watercolour plate of butterfly specimens|
Deudorix maudei File:Deudorix littoralis TypesMFUpAC1.jpg|alt=Photograph of two pinned butterflies with notes above|
Deudorix littoralis (male & female types) File:Bulletin of the Hill Museum v1 1921 Plate VI.jpg|alt=Book page showing watercolour plate of butterfly specimens|New
Delias from Buru File:Bulletin of the Hill Museum v1 1921 Plate VII.jpg|alt=Book page showing watercolour plate of butterfly specimens|New
Delias from New Guinea and Buru File:Bulletin of the Hill Museum v1 1921 Plate VIII.jpg|alt=Book page showing watercolour plate of butterfly specimens|New
Delias from New Guinea File:Bull Hill Mus v1 Plate IX.jpg|alt=Book page showing watercolour plate of butterfly specimens|New butterflies from Buru and New Guinea File:Bull Hill Mus v1 p594 Plate X.jpg|alt=Book page showing watercolour plate of moth specimens|New
Sphingidae File:Bull Hill Mus v1 p594 Plate XI.jpg|alt=Book page showing watercolour plate of moth specimens|New Sphingidae File:Bull Hill Mus v1 Plate XII.jpg|alt=Book page showing watercolour plate of butterfly specimens|New
Zygaenidae File:Annalsmagazineof8151915lond 0665 with explanation.jpg|alt=Book page showing watercolour plate of butterfly specimens|
Milionia, four others File:JJ Joicey cabinet Haslemere Educational Museum drawer no 14.jpg|alt=Photograph of a drawer of pinned butterflies|South American
Papilio File:JJ Joicey cabinet Haslemere Educational Museum drawer no 14 close-up.jpg|alt=Photograph of pinned butterflies with notes under each|South American
Papilio (detail) ==Legacy==