Direct monitoring of the electrostatic charge of house-flies (Musca domestica L.) as they walk on a dielectric surface

Charge build-up on walking Musca domestica was monitored in real time using an electrostatic voltmeter attached to an individual fly by a fine copper wire. Simultaneous video recording of behavioural movement was analysed by Inchworm©. Charge accumulation by the fly moving on PVC was positive and directly proportional to distance walked; as a consequence the rate of charge accumulation was directly related to the walking speed. Plateauing (saturation) of charge was prevented from occurring due to the increased capacitance caused by the large amounts of conductive material attached to the flies and the short distances travelled. This technique also allowed the effect of small surface charges to be observed; a positively charged acetal surface caused a rapid positive charge increase relative to distance walked, while negative charges acted against the tribocharging and reduced rate of positive charge accumulation. This work provides important information about the relationship between insect behaviour and charge accumulation with implications for the development and design of novel control strategies utilising electrostatic powders to adhere to the charged surfaces of insects or other organisms.