Overlay of the 8 μm-image (in red), the optical (DSS2 R, in blue), and millimeter (CO(2−1), green contours) images of the region. The yellow crosses indicate the position of the 2MASS pointo sources with IR excess, while the white and green crosses indicate the IRAC class I and class II sources, respectively. Finally, the red crosses indicate the position of CV Ser and Ser OB-1, -2, -3, -63 and -64.