Infrared excess (measured by the spectral index n) as a function of age for all spectroscopically confirmed members having log g = 3.5−4.0 that fulfill the criterion described by CSL to identify possible members of the Lupus clouds. The sample includes those objects already identified in previous works. Filled circles represent objects in the “on-cloud” population as defined in the text (see also Fig. 9), and open circles are members of the dispersed population.