He is remembered for his Arabian expeditions. In 1945, an entomologist, O.B. Lean, acting on behalf of the Middle East Anti Locust Unit (MEALU), hired Thesiger to search for locust breeding grounds in southern Arabia. This led to two crossings of the great Arabian desert, the Rub' al Khali or Empty Quarter, and travels in inner Oman. He rode camels in the company of Bedu guides through remote areas that were potentially dangerous on account of tribal tensions and the opposition of local rulers to the presence of foreigners.