In 1880 he visited India, accompanied by Frederick Du Cane Godman and the two visited Allan Octavian Hume before proceeding to Sikkim. He also made collection trips to the United Provinces, the Punjab, the Central Provinces, Bengal, South Canara and Travancore. Along with T. Edwards, Elwes wrote a monograph on the Oriental "Hesperiidae". He also made a trip to the Altai region in 1898. His posthumously published "Memoirs" (1930) includes a chapter describing his visit to Nepal in 1914, at a time when Europeans were seldom admitted. He also mentions an unnamed companion, now known to be the English naturalist Aubyn Trevor-Battye, who took some of the photographs used to illustrate this chapter. Elwes was famous for his breeding of "Nerine" and "Eremurus". Horticulturalist and garden writer Edward Augustus Bowles noted that he was specially interested in "Arisaema", "Crinum", "Crocus", "Fritillaria" and "Iris", as well as "Kniphofia", "Paeonia" and "Yucca". Bowles' memoir in Elwes' posthumous biography offers most information about the Colesbourne garden, but even this is scanty.