A technique is described whereby a small bulk of grain can be broken down, all insects infesting it recovered and their positions recorded. A Perspex box, 12 inches cube, is loaded with 64 three-inch-cube bags of Terylene net (10 meshes to the inch) each holding 390 g. of Manitoba wheat, and the test insects (adult grain beetles) released on the surface, after which the box is sealed and left in darkness for the required time. The bags are then removed, the insects sieved out, and their numbers and positions recorded, thus enabling the pattern of group dispersion to be plotted. The net used did not appear seriously to impede the movement of the adults of Sitophilus granarius (L.), the largest species used in the study. Temperature gradients may be introduced and measured by thermocouples built into the bulk.