[show abstract][hide abstract] ABSTRACT: A critical step in understanding mate choice is determining which phenotypic characteristics are used in mate assessment. Relatively little is known about the mating system of mosquitoes, including the role of mate choice. Recently, we described acoustic interactions between males and females that may play a role in courtship behavior in mosquitoes. Here, we present evidence that frequency of flight tone stimulus modulates harmonic convergence behavior of the malaria mosquito, Anopheles gambiae. Signals varied by body size, with large individuals producing significantly higher frequency flight tones than small individuals. Both sexes responded with shorter latency to higher frequency tones, demonstrating their ability to acoustically distinguish between large (and more fecund) versus small potential mates. Our results suggest that tonal variation within a mosquito species is perceived and suggest that flight tone frequency has potential utility for mate assessment in mosquitoes. Copyright 2010, Oxford University Press.