(With 9 plates and 2 figures in the text)
Wing deformations were studied in representatives of several hymenopteran families during free Right in hovering or near hovering conditions. The claval furrow, costal break, stigma and a variety of flexion lines occupying the wing apex are all involved in regulating forewing profile during the flight cycle in lchneumonidae and Tenthredinidae. In these families, as well as in the sphecid Sphex rujocincius, the median flexion line of the hindwing is also active in the terminal stages of supination. The plaiting fold of the vespid forewing plays an important role in profile control during the upstroke, reversing its polarity compared to rest. Little wing distortion was observed in the large scolids Scotia flavifrons and S. hirta, possibly attributable to the presence of strengthening ridges and grooves in the wing apex.