1 Bioacoustic methods play an increasingly important role for the detection of insects in a range of surveillance and monitoring programmes. 2 Weak-flying insects evade detection because they do not yield sufficient audio information to capture wingbeat and harmonic frequencies. These inaudible insects often pose a significant threat to food security as pests of key agricultural crops worldwide. 3 Automatic detection of such insects is crucial to the future of crop protection by providing

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... al information to assess the risk to a crop and the need for preventative measures. 4 We describe an experimental set-up designed to derive audio recordings from a range of weak-flying aphids and beetles using an LED array. 5 A rigorous data processing pipeline was developed to extract meaningful features, linked to morphological characteristics, from the audio and harmonic series for six aphid and two beetle species. 6 An ensemble of over 50 bioacoustic parameters was used to achieve species discrimination with a success rate of 80%. The inclusion of the dominant and fundamental frequencies improved prediction between beetles and aphids because of large differences in wingbeat frequencies. 7 At the species level, error rates were minimized when harmonic features were supplemented by features indicative of differences in species' flight energies.