As an explorer he took part in an expedition to Kamchatka between 1920 and 1922 along with Sten Bergman and Eric Hultén.

He then traveled back to Kamchatka in 1924 along with his fiancée, the journalist, writer and explorer Ester Blenda Nordström and did not return from the Soviet Union until 1930.

[1] Malaise then set out on another expedition of his own to northern Burma between 1933 and 1935, with Ebba accompanying him on the trip.

During this trip he collected some 100,000 insects, many of these totally unknown to entomology before Malaise's endeavor.

In his later years he spent most of his time building up a large art collection, including works of Rembrandt.