Technical Abstract: We addressed the relative importance of vertical and horizontal visual cues in nest location by females of the solitary bee Megachile rotundata. We compared vertical versus horizontal displacements of a nest block in the first experiment and of a proximal landmark in the second experiment. In a third experiment, we removed either vertical or horizontal proximal landmarks. Bees responded to changes applied to the nesting area by increasing nest location time and displaying behaviors consistent with confusion (hovering flights, reorientation flights, wrong nest visitations). The nest block displacements revealed a higher level of disorientation with horizontal displacements than with vertical displacements. Proximal landmark displacement led to disorientation with a horizontal displacement, but not with a vertical displacement. Removing proximal landmarks elicited disorientation, regardless of the orientation of the remaining landmarks.