A miniature solar cell was used to generate electrical waveforms from light reflected off the wings of individual insects in free flight. These waveforms contained harmonic patterns with the wingbeat frequency as the fundamental. Differences in harmonic patterns produced by Culex pipiens and Cx. quiquefasciatus (Diptera: Culicidae) were used to classify individuals even when they shared the same wingbeat frequency. Results indicate that harmonic patterns in optically-sensed wingbeat waveforms can be used as signatures for automated classification of flying insects by remote sensing instrumentation.