[1] He joined the Dominion Entomology Branch in Ottawa (now the Canadian National Collection of Insects [CNC], Agriculture Canada), where he would work from 1922 or 1923 to 1928.
[2] During this period, he also researched and published on the Diptera collected from the Lang-Chapin expeditions to the Belgian Congo that the American Museum of Natural History had conducted from 1919–1925.
One of his first activities with the museum was an expedition to Barro Colorado Island (then part of the Panama Canal Zone) from December 1928–February 1929 cataloguing Diptera in the region.
Curran was awarded a Doctor of Science from the University of Montreal in 1933 with his thesis "The Families and Genera of North American Diptera".
He received a promotion to full Curator of Insects and Spiders at the Museum of Natural History in 1947, and would serve the rest of his career there until his retirement in 1960.
[4] In his later career, rather than the academic monographs he wrote earlier, he began publishing books and articles aimed at a popular audience, including submissions in Natural History magazine.