Crosses: HAeBe sample from Acke et al. (2009) and solid circles: IMTT stars in our sample. Black indicates a Group I source and red a Group II source. The average uncertainty in the measurement is displayed in the top right corner of the panel. Left panel: relationship between the spectral slope from 13–30 μm and the 7 μm excess. Compared to the HAeBe stars, there is a lack of IMTT stars with a 7 μm excess above 4 magnitudes. Right panel: color comparison with the Herbig stars reveal that the distribution is similar to the HAeBe population. The location of V2149 Ori is marked.