Nest building behaviour of Celonites fischeri at nest F: 27 Following the orientation walk the female has stopped and is touching the substrate with her mouthparts at the place where she will later construct the basal end of the new cell during the subsequent visits. Note that she is not carrying a soil pellet 28 The female has moved slowly downwards keeping her mouthparts into contact with the outer surface of cell F129 The female is building parts of the basal cell wall of cell F3 standing on the surface of cell F1 30–32 The female holds on to the wall of the cell F3 adding soil pellets in the form of semi-circular figs. The hind legs are used as abutment while the material is applied with the mouthparts from the inside 33 The female is sealing cell F2.