Infrastructure, as a potential legacy of transnational scientific collaborations, is usually seen as extrinsic to the immediate production of knowledge. But cumulative collaborative scientific workwhat scientists actually do together; the ways in which they act on the world and transform our understanding of itcan also help create durable enabling environments for ongoing scientific practice. Project Locustox began in 1989 as a pilot to evaluate the environmental effect of locust control pesticides in the Sahel. It was prolonged through additional project phases over the next decade; in 1999, a locally-administered permanent ecotoxicological research centre was established in Senegal. Central to this project was the creation of Sahelian bio-indicators. The work of indicating, which was largely performed with and by insects, can be described as enacting infrastructure. Insects formed an axis along which data and expertise were accumulated, and, as a result, they were stabilized as durable toolsas bodies, colonies and the techniques for manipulating themfor future Sahelian ecotoxicology. Considering insects as producing infrastructure invites a reflection on the possibilities and difficulties of scientific capacity-building in the Global South. Specifically, examining the temporal extensions of indicating work leads to an account of how sustained investment in continuous collaborative scientific work can draw together biological entities, techniques, knowledge, materials, working relations and institutions to build durable capacity for science; but insect indicators also reveal the costs of and obstacles to maintaining the integration of methodological, material and institutional components of infrastructure.