(a) Line drawing of the initial two-choice test arrangement similar to that used by Phelan et al. (1991) with the exception that a ‘whole’ bee is used in place of extract of cuticular compounds. The slide cover with 4 mm holes rests on a wire support with the bees inserted from below. (b) Line drawing of modified two-choice arrangement with bees mounted using coaxial straws, the inner straw passing through the 4 mm dia. holes in a plastic slide cover. The two bees were inserted into the inner straws, wider straws on the outside went over the wings and legs and the thoraces were pushed together to allow the plural hair to overlap. The slide cover rests on a wire support.