The sensory abilities of insects are of great scientific interest. As an example, a biosensor on the basis of an insect antenna has been developed. With this sensor, organic odour molecules, like cis-3-hexen-1-ol, can be detected in concentrations down to the ppt range. To characterise the insect antenna as the receptor part of the biosensor in more detail, measurements based on impedance spectroscopy have been performed in this work, employing various conditions: the impedance of the antenna was observed to vary with the age, the applied bias voltage and the amount of applied odour. Hence, it could be shown that the antenna is not just a passive electronic device, but reacts actively to some parameters such as voltage or odour concentration.