NIRS age and species prediction for semi-field reared An. arabiensis and An. gambiae s.s . as determined from a cross-validation. Panel A (An. arabiensis) and B (An. gambiae s.s.) indicate the actual age against the predicted age. The horizontal dotted line in Panel A and B separates young mosquitoes (<7 d) from old ones (≥7 d). Panel C shows the actual species (1 = An. arabiensis and 2 = An. gambiae s.s.) against the predicted species for 1, 5, 7, 11, 12 days old An. arabiensis and 1, 3, 5, 9, 10 days old An. gambiae s.s. The dotted line in panel C is the classification cut off point for the two sibling species (<1.5 for An. arabiensis and >1.5 for An. gambiae s.s.).