The age of mosquitoes is a crucial determinant of their susceptibility to infection, probability of survival to transmit pathogens and tolerance to insecticides. We investigated changes to the abundance of proteins found in heads and thoraces of Anopheles gambiae and Anopheles stephensi as they aged. Protein expression changes were assessed using two-dimensional difference gel electrophoresis and the identity of differentially expressed proteins was determined by using either matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry or capillary high-pressure liquid chromatography coupled with a linear ion-trap (LTQ)-Orbitrap XL hybrid mass spectrometer. Protein biomarkers were validated by quantitative Western blot analysis.