Leech was born of John and Elizabeth (neé Ashworth) Leech in Bank Hall, near Preston, Lancashire. His father was a wealthy merchant.
Leech was educated at Eton College and Trinity Hall, Cambridge. He lost his right hand in an accident while partridge shooting in Cambridge.
In 1889 Leech married Beatrice Ellen Leatthias, daughter of wealthy New York businessman Henry Leatthias. They went to live in Hurdcott House, Barford St Martin, Wiltshire.[2]
Anonymous (1901). "Leech, J. H." Entomologist. 34: 33-38.
Gilbert, P. (2000). Butterfly Collectors and Painters. Four Centuries of Colour Plates from the Library Collections of the Natural History Museum, London. Singapore: Beaumont Publishing Pte Ltd.
Inoue, H. (2005). "John Henry Leech (1862–1900)". The Pioneers of Moth-Fauna of Japan. 1 Yugato.
Verrall, G. H. (1900). Proceedings of the Entomological Society of London.
Internet ArchiveCatalogue of the Collection of Palaearctic Butterflies Formed by the Late John Henry Leech, and Presented to the Trustees of the British Museum by His Mother, Mrs. Eliza Leech (1902) British Museum (Natural History.
Internet Archive Leech, John Henry On Lepidoptera Heterocera from China, Japan, and Corea (1897?) and BDH Volumes 1 and 2