We all have our hobbies but Alexander Macleay’s interests in natural history, insect collecting, botany, horticulture and landscape design were obsessions that saw him teeter on the brink of bankruptcy over many decades. From 1798 to 1825 he served as the secretary of the Linnaean Society in London, a gentleman's scientific club named after Linnaeus, the father of today's classification system for plants and animals – and by 1825 his insect collection was said to be the largest of any private collector. Chiefly interested in lepidoptera – butterflies and moths – his collection also housed important specimens from India, South America, North Africa and Australia. This included specimens from Captain Cook, and Surgeon-General John White, who came to Sydney on the First Fleet. The dispersed Macleay collections have found their way to the Australian Museum, Royal Botanic Gardens Sydney, the State Library of New South Wales and Parliament House, Sydney.

A selection of Macleay’s original insect cabinets are on loan to the Elizabeth Bay House library from the Macleay Museum at the University of Sydney, which Macleay’s nephew endowed in 1888.