In a population of Ammopbila sabulosa, hunting behaviour was followed in the field by direct observations and experimental trials. Each nest was opened immediately after its provisioning (in a non-destructive way) in order to record prey dimensions, stings distribution (by stereo-microscopical analysis) and egg position. Subsequently, caterpillars were put back in the brood cells and the nets closed again. Distribution of stings and eggs on caterpillars appeared asymmetrical: throat, 2(nd) and 3(rd) abdominal segments were significantly more stung than the other parts; the eggs were laid significantly more often on the 3(rd) and 4(th) abdominal segments. In addition, a dimensional analysis was carried out on the A. sabulosa population and on the caterpillar prey, and a histological analysis was performed on some stung caterpillars.