Who Killed 'Malagasy Cactus'? Science, Environment and Colonialism in Southern Madagascar (1924-1930)

The eradication of 'Malagasy cactus' (a prickly pear Opuntia) by a cochineal insect during the late 1920s had a profound impact on the political economies of southern Madagascar, causing extensive hardship to local peoples and their cattle and changing irrevocably the relationship between this arid region and the colonial state. Yet the circumstances surrounding this event have never been explored in any depth. This paper initiates its study by examining the evidence for the allegations that have been made of complicity on the part of the French colonial regime. It explores the conflicting discourses on 'Malagasy cactus' that divided the colonial administration, demonstrating close links between the campaign to eradicate the plant and the 'social policy' (politique sociale) that became dominant under Governor General Marcel Olivier (1924-1930). It reconstructs the history of the introduction and propagation of the insect, highlighting the role of ideologically-motivated scientific advisors, committed to the 'development' (la mise en valeur) of the colony and familiar with the biological campaigns against prickly pear in Australia and South Africa. Proving difficult to categorise in terms of models of colonial power and imperial science, above all this case study underscores the factor of chance that exists in colonial projects alongside the Orwellian logic. For if, on the one hand, the demise of 'Malagasy cactus' appears highly motivated when viewed against policies that sought to exploit the human and natural resources of Madagascar on an unprecedented scale, on the other hand, a review of the scientific literature on the control of Opuntiae by insects suggests a strong element of contingency in the affair.