Pick Your Poison: Insecticides and Locust Control in Colonial Kenya

Literature on the use of insecticides in the tropics after 1945 is preoccupied with the WHO’s Malaria Eradication Programme. This scholarship describes a form of technological hubris in which scientists rushed to deploy the quick fix of DDT on the widest possible scale, fuelled by belief in the power of Western science and buoyed by Allied victory. This paper focuses on trials to control locusts in Kenya after 1945 using synthetic insecticides to tell a different story. It shows that discussion about synthetic insecticides in Britain’s African colonies was not characterised by calls for rapid and far-reaching application of new chemicals. Caution arose in part because of concern about the costs of new programmes. This reflected the weaker economic position of Britain in comparison to the USA, backers of the WHO programme, but more importantly, new locust control substances such as gammexane were evaluated in Kenya against pre-existing ones. In other words, the notion that DDT and related chemicals were wonder weapons of such power that they marked a radical departure from past measures, and rendered all previous insect control methods obsolete, is not borne out by this study. The use of the new insecticides was dependent upon calculations of advantage versus cost in comparison to well-established existing methods. In addition, previous experience with arsenic bait and pyrethrum shaped the testing and deployment of gammexane in significant ways, including evaluation of its toxicity. The perception of the new chemicals as part of a continuum of poisons also informed the attitudes of Kenyan herdsmen. Their suspicion of gammexane was not merely the result of a distrust of Western science and the colonial government, but arose directly from the experience of seeing their cattle poisoned by arsenic bait during the interwar years.