He returned to graduate study at Harvard University with an extensive collection of insects and vertebrates, including a diversity of bird skins, which formed the basis for a 1931 article.
[1] From 1931 to 1932 he was a member of the Harvard Australian Expedition (1931–1932) led by William Morton Wheeler (his thesis advisor) and returned with a collection of a huge number of insects and 341 mammals.
[4][5] Darlington was a key member of the six-man Harvard Australian Expedition (1931-1932) sent on behalf of the Harvard Museum of Comparative Zoology (MCZ)[4][6] for the dual purpose of procuring specimens - the museum being "weak in Australian animals and ... desires[ing] to complete its series" - and to engage in "the study of the animals of the region when alive.
He served in the Sixth United States Army during Operation Cartwheel and subsequent campaigns before retiring as a major in April 1944.
The couple and their son, Philip Frederick Darlington, spent eighteen months in 1956–1957 for a field study, camping from a truck in the Australian outback.
Collecting alone in the jungle, he ventured into a stagnant pool by stepping carefully onto a submerged log, but a full-grown crocodile swam up and attacked him.
He was in a cast for several months, convalescing at Dobodura, Papua, where he perfected a left-handed technique for collecting insects: Have someone tie a vial to the end of a stick.