During the 1960s, the relationship between ecological theory and pest control practice was the subject of controversy between two groups of entomologists, one based in California and the other in Canada. Both groups were committed to the development of an `ecological' pest control strategy based on the integration of `biological control' — the use of predators and parasites to control pest populations — and the dominant chemical approach. Yet, they disagreed on the precise details of the relationship between ecological theory and the formulation of guidelines for the development of this integrated strategy. Consideration of institutional and conceptual problems shows that these different perspectives were shaped, but not necessarily determined, by the institutional context within which they were articulated. Attention is therefore drawn to the complexity of the relationship between ideas and institutions, and to the need for a broader approach to historiographical practice.