Historians, anthropologists and other social scientists have long lamented the dislocating effects of the partition of the Ottoman Empire upon the region’s nomadic populations. For the Bedouin, the era of the British and French Mandates is often characterized by their ‘encapsulation’ and sedentarization, as new border regimes, commercial restrictions and passport controls militated against seasonal migration, spelling lasting damage to the pastoral economy. This paper examines how – in the wake of war, famine and drought across the Syrian Desert – Bedouin groups were still able to turn their liminal position to advantage. As the new mandatory authorities struggled to control the desert borderlands of the Middle East, ordinary Bedouin could, in the right circumstances, become anything but ‘marginal’. The paper re-examines Bedouin possibilities in this period by foregrounding a particular problem of colonial governance, in which questions about the power of borders, nomadic agency, and colonial authority in the desert intersected: the British Empire’s campaigns against the Desert Locust (Schistocerca gregaria). In the late 1920s, and again in the 1940s, locust swarms surged across the new boundaries of the former Ottoman Empire, posing a threat both to food security and to the legitimacy of colonial rule. In the course of a new search for the insects’ “permanent breeding grounds” – far from the towns and rivers where colonial power was most assured – colonial officials came to rely closely on Bedouin information and Bedouin labour along the region’s desert borderlands. The paperwork generated by these interwar ‘anti-locust’ campaigns (a sign of the anxiety they provoked among the authorities) offers us a rare glimpse into the life of ordinary Bedouin, and into how their location at the spatial limits of colonial authority became a resource that some were able to exploit. Tracking this relationship reveals the slow and patchy nature of the growth of colonial control over these new boundaries; the agency of ordinary Bedouin in securing paid labour (including outside the channels of patronage controlled by Bedouin shaykhs); and the extent of their capacity to negotiate with the colonial state.