During the eighteenth century, the discovery of sexual reproduction in insect species prompted the demise of spontaneous generation and new developments in natural history, theology, and political economy. The sexual lives of insects prompted debates on whether insects were governed by desire, free will, and even marital tendency. Fuelled by the democratisation of microscopy, early modern entomology took a new turn and breadth: the study of insects and of their sexual lives provided unexpected new insights into human sexuality, reproduction, and (...) Malthusian fears of overpopulation. This article surveys the intellectual culture of entomology and natural history during the crucial decades when entomologists worked to quantify the reproductive capacities of insect species. Assessing the influences these entomological works had within political economy and theology, we argue that the sexual lives of insects − once analysed and delineated − influenced familiar ideological features of the intellectual landscape of the late Enlightenment, particularly in the theological philosophies of northern Europe and in the political economy of population in Britain. (shrink)