He was a specialist on predatory insects, especially in the fly families, Asilidae and the Empididae.
Hobby was born in Southampton where he became interested in the insects in the New Forest as a schoolboy.
He took part in the Oxford expedition to Sarawak in 1932, and was a Fellow of Wolfson College from 1965 to 1973.
He married Marcia Prestidge in 1937, with whom he worked on the editorial board of the Entomologist's Monthly Magazine.
His hobbies included playing chess, and he was also a keen swimmer and water polo player, who served as an examiner for the Royal Life-Saving Society.