Left-hand panel: ([8.0], [3.6]−[8.0]) CMD of LMC and SMC objects in the SAGE survey. Only every tenth star is plotted. The line at [3.6]−[8.0] = 0.8 mag indicates the blue limit of red AGB stars, and the two other lines indicate the limits of the region that is mainly occupied by background galaxies (see text). Top right-hand panel: ([3.6]−[4.5], [5.8]−[8.0]) CCD of all sources that are located in the upper right of the CMD delineated by these lines. Bottom right-hand panel: same diagram with synthetic CCD based on GS18 for 29 SMC and 133 LMC O- (open circles) and C-rich (filled circles) AGB stars with pulsation periods longer than 450 days. The pulsation periods of the objects marked in red are derived from K/K_s or WISE-band data, and the black points are derived from optical data (OGLE, EROS, and MACHO). The background sources in this panel are randomly picked from the S³MC survey (Bolatto et al. 2007).