4 - Fighting the Angoumois Grain Moth: Henri-Louis Duhamel du Monceau and his Network of Entomological Observers

Summary

In the spring of 1760, the controller-general of finances of the kingdom of France, Henri Léonard Jean-Baptiste Bertin (1720–1792) received an alarming report on the devastation caused by an infestation of insect pests in the wheat fields of the western province of Angoumois. Christophe Pajot de Marcheval (1724–1792), the intendant of the généralité of Limoges, informed Bertin that the crops in Angoumois had been devastated for several successive years by an insect that consumed the grain on the stalk before the harvest, leaving the inhabitants of the province without sustenance and unable to pay their taxes. Even more cause for alarm was that these insects were ‘spreading with fury in neighbouring jurisdictions’, and had already begun to advance upon the neighbouring provinces of Poitou, Aunis and Saintonge. Fearing that this ‘contagion might spread throughout the kingdom’, Bertin summoned two naturalists from the Académie Royale des Sciences, Henri-Louis Duhamel du Monceau (1700–1782) and Mathieu Tillet (1714–1791), both of whom had prior experience of the study of agricultural blights, and instructed them to travel to Angoumois in order to ‘conduct the investigations necessary for putting an end to this calamity’.

Often described as poor, isolated and backward by historians of ancien régime France, in fact the province of Angoumois underwent a period of accelerated economic development and integration in the period that preceded the mid-century reforms of the intendant Anne-Robert-Jacques Turgot (1727–1781). Farmers in Angoumois devoted an increasing proportion of their labour to the commercial cultivation of wheat. The construction of a dense network of roads between 1715 and 1760 connected rural settlements in the province to other localities within the généralité of Limoges and beyond, spurring the development of a carefully regulated, but brisk trade with the surrounding cereal-deficient provinces. Yet the extension of commercial wheat cultivation and the multiplication of trade networks, as Duhamel du Monceau and Mathieu Tillet came to recognize, provided favourable material conditions for the proliferation and spread of invasive insects like the Angoumois grain moth (Sitotroga cerealella).