ABSTRACTThe digging movements of the isolated ovipositor assembly of female locusts were filmed and analysed. The interpretation of the movements was compared, quantitatively, with observations on the intact ovipositing insect. The following major points were revealed. (i) The thrust of the ovipositor is at an angle to the axis of the hole. This allows the opposite side of the hole, rather than the very small inertia of the abdomen, to provide the reaction to the thrust. (ii) The ovipositor valves have different functions: the lower pair levers the abdomen down, the upper pair digs the hole. (iii) The maximum rate of longitudinal movement (2·8 mm s‐1) and the observed maximum displacement per digging cycle (2·0 mm) can account for digging speeds and displacements noted in the intact digging ins