Summary
Physiological age grading methods for bloodsucking Diptera of medical importance which shows gonotrophic concordance are reviewed. In the first part the changes which occur in mosquitoes following a blood meal are outlined and the theretical basis for age determination discussed. In the second part the methods applicable to Culicidae, Simuliidae, Phlebotomidae, Ceratopogonidae and Tabanidae are given. Extensive use of photographic material is made where this is a useful diagnostic aid in the interpretation of ovarian dissection.