Catch basins are a common breeding site for mosquito larvae in urban areas. The arrival in Spain of the Asian tiger mosquito, Aedes albopictus, has turned catch basins into a challenging public health issue in some areas such as the Baix Llobregat region, where more than 135,000 units are treated per year in a large-scale application program. Although biorational larvicides are used, modern formulations providing longer efficacy periods could lead to manpower savings. Laboratory indoor trials are presented on the formulation VBC60035 (Vectomax™ FG), which is under registration in Spain. Indoor microcosms simulating real catch basins were treated and recolonized weekly using insectary-reared Ae. albopictus larvae. The trial took place over 2 seasons in the same water at dosages of 10, 50, and 577 kg/ha. At all 3 concentrations, the efficiency was close to 100% for up to 345 days posttreatment with 14.1% mean mortality in the control. Field factors including flushing, bacterial degradation, and toxic effluents in the drainage pools are discussed as limitations of indoor tests.