Biodiversity loss is occurring globally with negative impacts on ecosystem function and human well-being. There is a scientific consensus that diverse environmental and anthropogenic factors are altering different components of insect biodiversity, with changes occurring at all levels of biological organisation. Here, we describe how uncertainty around specific trends and the semantics of 'decline' in relation to insect biodiversity have been leveraged by denialist campaigns to manufacture doubt around the insect biodiversity crisis. Disinformation is one of the biggest threats to social cohesion and environmental integrity globally. We argue that scientists, academic institutions, policymakers, and journalists must combat denialism by relying on robust research, supporting efforts to communicate scientific uncertainty more effectively, and build consensus on the global impacts of insect biodiversity loss.