By displacing Rachel Carson’s approach in Silent Spring to another time, another place and another family of pesticides, this paper tells the story of the wide adoption of arsenates, despite their known toxicity, to control the then newly present Colorado potato beetle in Western Europe from the 1920s to the 1950s. Although arsenate use entailed health and environmental risks, it was extended to other insect pests because this control method proved effective. The Colorado beetle appears as the matrix around which plant protection was developed in France and Germany. The regulations, administrative structures and habits that revolved around the wide use of arsenates then paved the way for the quick and massive adoption of organochlorides after 1945.